Volume 2 / Part 2 — APPENDIX.

SULPHUR IN ICELAND.

SECTION I.

Let us begin this subject with an extract from Hr O. Henchel’s Report on the Icelandic Sulphur Mines, and on the Refining of the Sulphur. January 30, 1776. (Translated from the Danish).

I arrived at Krísuvík the 24th of June 1775, and immediately after my arrival I made preparations for examining the mountain of Krísuvík, with its mines and the surrounding neighbourhood. This mountain is situated two miles from the sea, the intervening space all the way from the sulphur mines being a tolerably level field, with only a few diminutive hills. The mountain stretches from north-east to south-west, and about two miles south-west from the mines it terminates in a plain, three miles of which are covered with lava. To north-east I did not examine the mountain more than three miles from the mines, because I found that in this direction the whole of it consisted of the same stuff, viz., of a very loose sandstone (Palagonite), except where the mines and the hot springs are to be found; there it consists of gypsum, and partly also of a red and blue “bolus,” which, in my opinion, has been sublimated by acid vapours, and partly thrown up by the hot springs. In some places these soft earths have become a hard stone, the cause, being, no doubt, that the access of the water has been stopped in these places, and when the acid vapours could not any more penetrate through this soft earth, it became hard by degrees.

In some places the above-mentioned gypsum is found to be tough and sticky, and when it is dried slowly it has a greasy touch; sometimes it is perfectly white, sometimes with red streaks, and one might take it for pipe-clay. One may therefore conclude, that by the acid, the effects of the rain and the sun and the rising heat, a fermentation has been brought about in this earth, and that it has thus become tough. Besides the already-mentioned variation, another kind of gypsum earth is found on the top of the mountain in hard sheets irregularly formed; here we probably see the effects of strong heat combined with absence of sufficient water, after the fermentation has taken place. In other places where this earth is saturated with sufficient acid, and partly dissolved by the same, and has, besides, a suitable or a natural degree of heat, so to speak, it is found in loose, reddish, and prismatic crystals. There is a considerable quantity of it, but it is never found deeper than from one foot to a foot and a half; the deeper you go the less solid it becomes, and at a depth of one foot it becomes quite fluid, because the heat is so strong, and the ground penetrated by warm vapours to such a degree that it cannot attain any solidity; in fire it loses its red colour. In short, this earth goes through so many changes, partly through the greater or lesser degree of heat, partly through a greater or less abundance of acids and water, and through the admixture of foreign substances, that it can almost bewilder one.

The blue “bolus” is found everywhere beside the boiling springs, and some of them are filled with it in such quantities that they are like a pot full of thick gruel. When the “bolus” has become hard it cannot be melted by the blow-pipe, but, in its natural condition, it attracts vapours from the air, and forms very fine white crystals, and at a distance they look like hoar-frost. This seems to show that this kind of stone must be impregnated with calcareous earth which has been saturated with vitriolic acid. That it must be this kind of earth in a hardened state is seen both from its form and from the flowers of pyrites that are mixed with it; for when one breaks off a piece of these earths in their soft and half-solid condition, the broken pieces have the same form, and are also interspersed with pyrites.

The red “bolus” is always found on the surface of the ground like the white gypseous earth, and is never covered by a bed of another kind; it is never mixed with the water of the boiling springs; there is no sublimated sulphur where it is found, although the subterranean heat in some such places is quite as strong as where that process actually takes place.

Several hot springs are to be found here, and most of them contain the blue “bolus,” but one contains white earth. These springs often disappear in one place, and break out again in another place where no spring has been before; the probable cause is that the narrow pipes under the ground, through which the spring is supplied with water, fill up by degrees; the strong heat transforms the water into very elastic vapours, which break through the ground where they find the least resistance, and thus a new hot spring is formed.

On a hill between the southernmost hot spring, called the Bath-room, and the more northerly springs, a hardened “bolus” is found; it is so brittle that it can easily be broken between the fingers; it is porous, and its holes are filled with hardened lime. At first I assumed this “bolus” to be a kind of lava partly dissolved by the atmosphere and the slow heat rising from the ground; the lime I took for a kind of salt, which had been embedded in the lava, and let loose by its solution, and then settled down into the holes of the “bolus.” But, upon closer examination of the solid state of this lime, and, after having tested it by aquafortis, by which it was brought to a high state of effervescence, I saw plainly it must be lime. I had tried to dissolve it in water, but without success; if it had been a salt let loose by the dissolution of the molten lava, it must have been more loose and in a somewhat crystallised state. My idea is that the lime must have been sublimated by the hot vapours when the lava was already thrown out; then it subsided into the holes of the lava and became hard. When I compared this earth with the lava of other places where volcanoes had been, from which the lava had spread far and wide, without undergoing any perceptible change or dissolution, I saw that this could never have been a lava. Although the lava of volcanic mountains is often confounded with slag produced by burning of the ground, I saw that this had never been melted to real slag; and it seemed to me therefore probable, that it must be a kind of hardened clay. I did not, however, find anything to confirm my conjecture until I came to Mývatn, where I found specimens of it in a soft and crude state.

The loose sandstone (Palagonite) already mentioned, which is found besides the most northern hot springs, is there much finer than in other places; it is of a slaty structure, and between the plates gypsum is found, so one might almost take it for alum plates. On the top of the mountain another kind of sandstone (trachyte?) is found; it is a good deal harder and burnt; it looks like millstone rocks from the Rhine, yet it is more porous; it is in irregular heaps, and never makes a whole mountain, as if it had been thrown over by earthquakes.

Near the boiling springs, where the ground is loose and porous, but especially where the heat has free ventilation through the above-mentioned gypseous earth, the sulphur is to be found. At the bottom it is dissolved and mixed with acid vapours; and when the sublimation has taken place, it becomes fixed in the outermost crust where there is a colder bed; and here it is found either in the shape of crystals, powder, or flowers; it is never deeper than one, two, or three inches under the surface, according to the greater or lesser degree of heat, or the greater or lesser porosity of the earth which forms the uppermost bed, as the sulphur bed itself, when it is in the shape of powder, is never more than three to six inches; and when in a crystallised form, never thicker than two to two and a half-inch, and three inches at the very highest.

These mines are not many, and do not cover a large space of ground; there are indeed a few spots here and there where sulphur is sublimated, but these spots are very small. The most important as well as the largest are the two mines highest up in the mountain; one of them is 120 yards long, and from 16 to 20 yards broad; the other is from 140 to 160 yards long, and from 20 to 40 yards broad. In these two mines the finest and best sulphur is found in the largest quantities. The bed covering the sulphur contains a great deal more of acids than the layer immediately below it, because the hot acid vapours rising from the depths below must keep the lower bed permanently acid and damp; the surplus acids are driven up through the sulphur, and that portion of them which does not unite with the sulphur, comes to the uppermost crust, where it is dried by the combined efforts of the sun, the air, and the wind. Here the acids are therefore more concentrated, and consequently able to dissolve some portions of the gypseous earth with which it has become united; in this condition it makes a kind of flowers of alum, which, however, are partly vitriolic or blended with iron. I tried to examine the purity of this salt by dissolving it in water. When the water had been filtered it had a green colour; thereupon precipitated with alkali, it gave a white precipitate; and when this was separated from the water, the latter became after a while quite yellow, as if it had been coloured with iron rust. This salt cannot really be called alum unless we should call it lime-alum. Like alum it has a nauseous taste, but more pungent and almost caustic. When, after dissolution, it has become solid by evaporation, it is not nearly as close as alum, and no crystallisation can be perceived in it.

As the sulphur is sublimated in the manner above stated, and by condensation becomes fixed in the cold earth at the surface, it will be seen that the opinion is erroneous, that sulphur is generated in earth penetrated and made porous by the air. My instructions were to find out, by blasting the rocks, whether any traces of sulphur were to be found in them; but blasting was out of the question on account of the softness of the ground, the great heat, and the large quantity of hot vapours. The rocks must, moreover, be at a great depth, since all attempts to find them with the earth-borer, which was fifteen feet in length, proved unsuccessful.

Close to the mines on the south side heat is seen to have been in the mountain formerly. Here the same kinds of stone are found as at the hot spring, and the yellowish gypseous earth as well. By some cause or another the heat has been removed somewhere else. I was convinced that sulphur must be found here, as it might have been covered with earth after the heat left; but all my diggings, both with the earth-borer and otherwise, proved unsuccessful.

With the earth-borer I tried to ascertain the difference of the beds where sulphur is sublimated, and of those where it is not, and where only a slight heat is felt. The first experiment was made in the northernmost mine. Below the sulphur I found a one-foot thick bed of the white gypseous earth; then there was a bed of fine blue “bolus,” or an earth impregnated with flowers of pyrites here and there. In this bed the heat began to increase, and when I came to a depth of three feet the bed became a little harder, but, at the same time, warmer and coarser, as if it were mixed with gravel; and thus it continued to the depth of fourteen feet, when it became a little softer.

I examined another place where no considerable heat was felt. The white gypseous earth continued to the depth of a foot and a half; and in this place it was harder and more solid than where the heat had a free egress. Then came the blue earth; uppermost it was somewhat loose, but farther down it became so hard and close that the earth-borer could hardly penetrate it; the lower down the more it became mixed with pyrites, and was filled with gravel, as it were. At the depth of twelve to thirteen feet it became a little looser as I thought. It was the same kind of earth all the way through; the heat was intense.

The third place which I examined was at the most northern point, beside a small hot spring, thick with blue earth. Uppermost there was red “bolus” to the depth of one foot; then a bed of purple and a yellowish one, three feet thick; then a purple and bluish one, one foot thick. The heat increased with the depth; here the bed became very hard, and I found the blue earth impregnated with pyrites. This bed was ten feet deep; at this depth the heat was so intense that the water trickling down from the upper beds boiled violently, and prevented all further progress.

By these experiments I found that the conditions necessary for the sublimation of the sulphur are: Firstly, A sufficient quantity of water to keep the soil loose and porous, that the sulphur may pass through it, and to drive the sulphur vapours upwards. Secondly, That the water must come from below; for when it comes from above, it cannot penetrate through the blue bed in the absence of the rising hot vapours which keep the bed porous; and in that case the bed becomes harder and harder, and prevents the sublimation of the sulphur.

I tried in several places, both with the earth-borer and otherwise, to discover some of the so-called dead mines, but without success. From the many experiments I made, I concluded that the volcanic mountains of Iceland must have been sulphur mountains or sulphur mines in the beginning; the blue bed became hard, and the sulphur vapours were thus prevented from being sublimated. Thus they became more condensed, and, at the same time, more elastic in the ground; then there arose in them a “heat-forming movement,” by which the whole ground, which is very sulphureous, became violently shaken, and subsequently ignited, causing tremendous destruction.

Mývatn.

Fremri-námar.

At Húsavík I obtained horses and workmen from the sheriff, and left that place the 9th of August, and arrived the 12th in the evening at the so-called Fremri-námar. At a distance of about one mile from the mines, there is a valley called Hellaksdalur, where there is a little grass, just so much as to give the ground a green colour, and this is the only green spot that is to be found here within a distance of many miles; yet there was not grass sufficient for the horses, but I had to bring with me hay for them, and water for the men. In this valley I spent the night, and the next morning, the 13th, I went to the mines, which are about ten Icelandic miles (11 indirect, 40 geographical) south-east from Húsavík, situated on the west side of a mountain called Herðubreið. On the top of the mountain there is a ridge or an eminence, from which there is an extensive view; but as far as the eye can reach in every direction, nothing can be seen but lava. This eminence is 1500 paces long, and equally broad, and about 120 feet high. On the top of the eminence there is a deep hollow completely round, and about 200 paces in diameter. From its shape it is called by the inhabitants a kettle. The south and west sides of this eminence, as well as the hollow itself, consist of lava, and it may therefore be concluded that the mountain has been an active volcano in olden times. On the north and east side the mines are found, and where these are the mountain consists of gypseous earth like that at Krísuvík. A large quantity of sulphur is said to have been dug from the dead mines here; but now they are rarely found, because they have been worked annually, and the sulphur is not generated afresh in these as in the live ones. Thirty paces from the end of the valley, and also on the side of the mountain, the first live mines are found. In the valley they are about 60 paces long, and from 20 to 30 broad. On the side of the mountain they are 200 paces long, and from 20 to 30 broad. On the east side of the mountain, 40 paces lower than the mines above mentioned, other live mines are found 220 paces long, and 40 to 50 paces broad. From all these the sulphur has been completely cleared away, because the sulphur found here was very good and pure. The soil is moderately damp, and the sulphur has just as much water as (when converted into steam by the heat) is sufficient to raise it up, and to keep the ground in a loose and porous condition, so the sulphur can be sublimated through it without hindrance. Yet it does not make the soil too loose; in that case, small particles of earth would rise along with the sulphur, become mixed with it, and thus make it impure. In the mines, which, according to my guide’s information, had been completely cleared of sulphur, there was already a new bed of sulphur one to two inches in thickness, but very impure. There are others which formerly yielded sulphur, now quite cold, and ruined. The destruction of the mines, as well as the impurity of the sulphur, arises from careless digging. When the peasants dig the sulphur out of a mine, and particles of earth and impurities are sticking to it, they clear away the largest lumps; but they do not take care not to let the impurities fall down where they had taken the sulphur, where some flowers of sulphur always remain. For although the uppermost sulphur is tolerably compact and crystallised, the lowest is loose. The reason is that the uppermost bed is made more and more compact by the sulphur rising from below, and the acid phlegm surrounding the sulphur vapours cannot evaporate; the small sulphur particles are thus prevented from immediate contact with each other, but are enveloped in the superfluous phlegm. This is the reason why the lowermost sulphur must remain in the shape of flowers until the hard crust is removed; then the phlegm is exposed to the air and evaporates, until the surface has become hard again. It will therefore be seen, that when the impurities fall into these loose flowers, and the fine sulphur is subsequently sublimated among them, the impurities will be imbedded in the sulphur, and must be taken out with it at a second digging.

Another reason for the impurity of the sulphur is this, that a man, coming to a mine to see how the sulphur is, thrusts his spade into the ground in various places, without first carefully removing the upper earth, whereby the sulphur and the earth become mixed together. If he does not think the sulphur good or abundant enough to be dug out at that time, he leaves the mine thus disturbed; and the rising sulphur is sublimated among the disturbed lumps of earth and sulphur, and the whole becomes a compact mass; it often looks quite pure, but turns out altogether different at the refinery. Thus a single man may in one hour destroy a great many mines that might have been excellent if more carefully handled.

One more cause of the impurity of the sulphur may be found, I think, in the following circumstance. When the peasants come to a good mine they take out all the sulphur that is to be found there, and do not take care how they tread down the loose earth below the sulphur; the down-trodden earth, over which the wind sweeps freely, becomes tough and hard when the heat from below is not strong enough to break through it, and thus keep it porous; thus the mine becomes cold and useless. In other places where the heat is strong enough to force the steam through the trodden earth, there is, however, this disadvantage: Firstly, It takes a longer time for the sulphur to arrive at a state of perfect sublimation than if the earth had remained in its porous condition. Secondly, The fresh sublimation will be impure. When one steps into the loose earth, deep holes, separated by thin ridges, will be formed. When the sulphur is formed in these holes, covering the ridges as well, it is evident that all these ridges must come out with the sulphur at a subsequent digging.

Those that work the mines must therefore be ordered: Firstly, To remove the earth before they dig up any mine, so that nothing shall fall into the sulphur. Secondly, When they remove lumps of earth from the sulphur, they must carry them outside the mine. Thirdly, When they work a mine, they must first remove the uppermost earth; they must not completely empty any mine of its sulphur: they should leave the utmost border standing; then run a trench along the whole length of the mine, then leave a ridge standing, and run another trench, and so on until they have reached the utmost border, which they are to leave standing. Thus the wind will be prevented from having a full sweep of the mine, and thus making it cold. These trenches ought therefore to run across the course of the most frequent winds; these are here, in my opinion, a north-wester and south-easter. After one year the ridges left standing might be taken with the same precaution as mentioned above. The workmen ought therefore to be as much as possible prohibited from stepping into the mines; every digger should take with him a board to stand on while he digs, and this he should move with him as he proceeds. By these means the mines might be saved from being unequally trodden down, and the digger might escape from burning his feet, which he now frequently does, by sinking through the loose and hot soil.

On the east side of the mountain, below the above-mentioned mines, a red “bolus” begins, stretching round the mountain from south to north until it meets with a sandstone mountain; between the mountain and this ridge of “bolus” there is a little sulphur mine, and here the gypseous earth is found below the sulphur as usual. Digging up the real “bolus,” I found it to be very loose and soft; it was full of holes, like the hardened one at Krísuvík, and the holes were filled with lime, very loose and gelatinous, and slimy to the touch. Under the “bolus” the earth was in many places hollow, and one hardly dared to tread there. Very hot vapours arise from the bottom, by which these earths are sublimated, for it is quite as hot here as in the sulphur mines. This is a very interesting circumstance, and well worth observing, that there are two places lying side by side, and presenting such a difference in the stuffs driven up from the bottom by the heat, which is equally great in both places. In one, however, sulphur is sublimated along with a strong acid, and in the other the above said lime is sublimated, and not the least acid is found in it.

Hliðar-námar.

The 15th I went to the so-called Hliðar-námar, which are about eighteen miles distant from the former ones. These are the largest of all the mines, and here too is the greatest heat; the sulphur is consequently sublimated in less time than in any of the others. At present there is a large quantity of sulphur here, but it is all in powder, or in the form of flowers; most of them are found in the mountains, as in the former places; and the sulphur bed is in many places six inches and more in thickness. The reason why the heat drives up greater quantities of sulphur here than in the former places is to be found in the looseness of the soil; it is not only much looser than in the former ones, but in some places even too loose and damp, which both makes the spot difficult to approach in order to dig, and fills the sulphur with earth and impurities, so as to make it useless. The reason why these mines are in such a good condition now is, that the sulphur brought from here to the refinery was not so well received as that which came from the Fremri-námar, or the so-called Theystarreykja-námar nearest to Húsavík. I admit that the sulphur found here is more mixed with earth and acids than in the other places; not, however, in such a degree as to offer any serious difficulties. But as the whole of the sulphur is in the form of flowers, and the earth immediately below it has nearly the same appearance, and cannot therefore be easily distinguished from the sulphur, the peasants do not, therefore, I think, separate the sulphur from the earth with as much care as where it is found in a more solid condition, and where the earth is more easily detected.

The mountain where these mines are situated stretches from north to south, and on the north side it goes a considerable distance beyond the mines. The same kinds of earth are found here as at Krísuvík, except the grey slate, of which there is none here, neither are there any variations in the gypseous earth; and very little of gypsum is to be found, which probably is owing to the higher degree of heat, or it may be because the heat has less interrupted egress, and consequently keeps the earth constantly porous. There is a larger quantity of the vitriolic alum. For the rest, the mountain consists of common sandstone. That even these mines have not been worked carefully is evident from the considerable number of ruined and cold mines.

Below the sulphur mountain on the east side there are three boiling springs; it is evident that the two farthest to the south, and situated close to each other, have been produced by an earthquake, because they are found in a rift in the mountain, and boil with such awful noise, especially the most southern one, that it can be heard 200 yards off, and the ground, which consists of bluish “bolus,” is shaken. Close to these hot springs is a large lava-tract, which spreads to the north to a considerable distance; it also winds round the southern point of the mountain, and crosses the path that leads to Fremri-námar, and spreads almost down to Reykjahlið. The ground is hot everywhere, and the hot vapours rise through the lava, and the whole is therefore continually steaming. About nine miles north of these mines is the mountain Krabla, where excellent mines are said to have been, but when the eruption of 1724 took place, it caused great destruction. One branch of the lava-stream coming from this mountain passed close by the mines on the west side and through the farm of Reykjahlið, the whole of which was destroyed, and at last the current flowed into the lake Mývatn. The lava thus produced was in various places hollow, as if the uppermost crust had been hardened by the air, and the still liquid lava which was under it flowed away. As the outmost crust cooled down by degrees, it contracted, and thus rifts were formed; in some places also it was not strong enough to support its own weight, and fell down. Crawling into these caves, I found a kind of salt which had been sublimated from the earth, and become fixed there. It had a bitter taste, and after being dissolved and dried again it formed square crystals, with a square point. It was easily melted by the blow-pipe.

Theystarreykja Mines.

The 31st of August I came to the Theystarreykja mines, which are about two miles from the refinery. A large quantity of sulphur is said to have been brought from these mines to the refinery, as they were very important ones, but now they are almost all cold, and it is only in a few of them that sufficient heat is found. Therefore, although four years are said to have passed since sulphur was taken herefrom, there are only four or five where it might be taken again. Nevertheless the heat seems in some of the cold mines to be breaking through so far that the vitriolic acid can be sublimated through the ground, as it has in combination with the dissolved lime formed the above-mentioned vitriolic salt. It is therefore to be hoped that many of these ruined mines may recover after a time, yet this is not certain. Here is again a clear instance of how the very best mines may be ruined in a short time by careless treatment. If, therefore, the still remaining mines, either here or in other places, are to be preserved, the peasants must be prevented from digging the sulphur.

The home-field of Theystarreykir is good though small, and has a fine situation; and to the north there is a large piece of uncultivated ground which might be made useful. Close to the farm is a hill called Bæarfell, where some of the mines are situated. It begins on the south side of the most southern mines, and continues in a northerly direction, then it takes a turn to the east and then again to the north. In the corner between the eastern and southern arms of the Bæarfell the best mines are found at present. There have been a great number of mines on the west side of the mountain, but these are now cold, except a few in the middle, where the earth is tolerably loose, and the heat can therefore sublimate the sulphur. Those, however, that are on the east side of the hill are quite cold, except two small ones high up in the hill, but there is sufficient heat in all these mines; and I am therefore of opinion that sulphur may be sublimated in them for the future. Some of the western ones are also found to be considerably hot, and it may therefore be expected that these ruined mines may recover in time. On the west side of these mines there is a large tract of lava. On the north side of the Bæarfell the home-field begins, and north of that again a piece of uncultivated ground; when beyond that, the lava reappears and takes an easterly turn. On the top of the Bæarfell there is a great deal of red “bolus,” and a strong heat under it. But sulphur is never sublimated with or through the red “bolus,” therefore it is not found here. Very little of gypsum is found in these mines. The warm springs are neither deep nor very hot, and the minerals are either sandstone, or hardened like those at Krísuvík.

All the sulphur mines which I visited in the north are in the following condition: Fremri-námar bad, because all the sulphur was taken away last year. Hliðar-námar good, because they have been saved the most. Theystarreykja-námar are worst, because the largest quantity has been taken from them. My advice is, therefore, to let Fremri-námar and Theystarreykja-námar rest for some time, and to work the Hliðar-námar only. When these have been emptied, the former two may be worked in their turn.

The Refining of the Sulphur.

The refinery is situated a few hundred paces from the factory of Húsavík, and consists of a sulphur hut; two store-houses, one for the raw sulphur, the other for the melted, or refined ore; a dwelling-house, with kitchen and outhouses, all built of turf according to the Icelandic fashion. The hut is about 20 feet long and 12 to 14 feet broad. In the middle of it is a small chimney, and on both sides of it two iron boilers are walled in; one is quite small, and holds only 1 cwt. of melted sulphur, the other holds 3 cwts.; the smaller one is very little used. Above the boiler a small board is inserted in the chimney, which reaches over the middle of the boiler; it has a hole at one end, through which a stick is put to stir up the sulphur; when its lowermost end reaches the bottom of the boiler, the uppermost is supported by the board, and he who stirs the sulphur can therefore move the stick more easily than if its upper end were loose. The other instruments are, an iron spade with holes, which is used for taking off the impurities floating on the molten sulphur. Then there are some wooden forms, into which the molten sulphur is poured. They are made of oak planks 3 inches thick, 12 inches broad, and 3 feet long. On one side of the two outermost planks, and on both sides of the two middle ones, three cylinder-shaped grooves are made, so that every half-cylinder groove of the two outermost corresponds with those on the middle ones, and those on the middle ones with each other. The planks are laid one on the top of the other, and kept together with an iron ring; in such a form nine bars can be made at the same time. A small iron sieve with narrow holes is put in the top of each hole, through which the sulphur is sifted when poured out from the boiler with a large iron ladle. When not used the forms are put into a tank filled with water, in order that the hot sulphur may not stick to the sides of the holes. This is completely prevented by soaking the forms in water. These are all the instruments used in the refining of the sulphur. The fuel used is some little wood sent by the Government, and for the rest peat, of which there is a good supply close by.

When the sulphur is to be purified, a slow fire is made under the boiler, and when it grows hot a small quantity, about two pounds, of raw sulphur is put in; this is stirred till it becomes hot; the fire must be slow, in order not to burn the sulphur, which might easily happen on account of the quantity of earth mixed with it. When the portion is quite dry and begins to melt, a little train-oil is poured in and stirred quickly, by which the earth unites with the oil, and floats on the top. As soon as this is melted, another portion of raw sulphur is put in; and when this is melted, another portion of oil, if required: this is easily seen; if the earth absorbed by the oil falls to pieces like ashes, it falls again into the sulphur, and oil must be poured in immediately. Thus the work is continued until the boiler is full. When the boiler is nearly filled with molten sulphur, a quantity of train-oil is poured on the top of it, and heated sufficiently. Then the fire is removed and the stirring discontinued. The impurities absorbed by the oil are removed with the iron spade described above. The forms are taken out of the water, put together, and raised on one end. The iron sieve described above is placed over the first form, and the sulphur poured over it from the boiler. When it is full the sieve is placed over the second one, then over the third, and so on.

SECTION II.

The next account that we have of the Krísuvík diggings will be found in the following extracts from “Travels in the Island of Iceland during the Summer of the Year 1810,” by Sir George Steuart Mackenzie, Bart., etc., etc., second edition, 1812.

Pp. 113, 114.—We set out towards the Sulphur Mountain, which is about three miles distant from Krisuvik. At the foot of the mountain was a small bank, composed chiefly of white clay and some sulphur, from all parts of which steam issued. Ascending it, we got upon a ridge immediately above a deep hollow, from which a profusion of vapour arose, and heard a confused noise of boiling and splashing, joined to the roar of steam escaping from narrow crevices in the rock. This hollow, together with the whole side of the mountain opposite, as far up as we could see, was covered with sulphur and clay, chiefly of a white or yellowish colour. Walking over this soft and steaming surface we found to be very hazardous, and we were frequently very uneasy when the vapour concealed us from each other. The day, however, being dry and warm, the surface was not so slippery as to occasion much risk of our falling. The chance of the crust of sulphur breaking, or the clay sinking with us, was great; and we were several times in danger of being much scalded. Mr Bright ran at one time a great hazard, and suffered considerable pain from accidentally plunging one of his legs into the hot clay. From whatever spot the sulphur is removed, steam instantly escapes; and, in many places, the sulphur was so hot that we could scarcely handle it. From the smell we perceived that the steam was mixed with a small quantity of sulphuretted hydrogen gas. When the thermometer was sunk a few inches into the clay it rose generally to within a few degrees of the boiling point....

Pp. 115, 116.—At the foot of the hill, in a hollow formed by a bank of clay and sulphur, steam rushed with great force and noise from among the loose fragments of rock.

Farther up the mountain we met with a spring of cold water, a circumstance little expected in a place like this. Ascending still higher, we came to a ridge composed entirely of sulphur and clay, joining two summits of the mountain. Here we found a much greater quantity of sulphur than on any other part of the surface we had gone over. It formed a smooth crust from a quarter of an inch to several inches in thickness. The crust was beautifully crystallised, and immediately beneath it we found a quantity of loose granular sulphur, which appeared to be collecting and crystallising as it was sublimed along with the steam. Sometimes we met with clay of different colours, white, red, and blue, under the crust; but we could not examine this place to any depth, as the moment the crust was removed steam came forth, and proved extremely annoying. We found several pieces of wood, which were probably the remains of planks that had been formerly used in collecting the sulphur, small crystals of which partially covered them. There appears to be a constant sublimation of this substance; and were artificial chambers constructed for the reception and condensation of the vapours, much of it might probably be collected. As it is, there is a large quantity on the surface; and, by searching, there is little doubt that great stores may be found. The inconvenience proceeding from the steam issuing on every side, and from the heat, is certainly considerable; but, by proper precautions, neither would be felt so much as to render the collection of the sulphur a matter of any great difficulty. The chief obstacle to working these mines is their distance from a port whence the produce could be shipped. But there are so many horses in the country, whose original price is trifling, and whose maintenance during the summer costs nothing, that the conveyance of sulphur to Reikiavik presents no difficulties which might not probably be surmounted.

Below the ridge on the farther side of this great bed of sulphur we saw a great deal of vapour escaping with much noise.

SECTION III.

Mr Consul Crowe’s Report (1871-72) supplies the following notices of mineral prospects in Iceland:

Mineral deposits, showing the presence of copper, iron, lead, and silver, are found in many parts of the island, but either from their poorness or the want of fuel, no attempt has been made to utilise them. Calcareous stone, marbles(?), and feldspath are also found; and large deposits of sulphur likewise exist in some districts, which at different times have been the object of commercial speculation. The sulphur mines at Krisuvik, in the south, are at present worked for foreign account, but, I believe, owing to their partial inaccessibility, and difficulty of transport, without much success.

The right of working sulphur mines at Myvatn, in the northern portion of the island, has recently been conceded by the Danish Government to an Englishman on a fifty years’ lease. They were worked some years ago for account of a Copenhagen house, but were abandoned in 1851, since which time they have remained closed. Many causes contributed to this result; the chief of which, doubtless, were, ignorance of the proper method of mining the sulphur, the cost of transport on horseback to the sea-board, and the want of remunerative demand.

Since then these conditions have changed, and there exists no reason why these mines should not be worked profitably. They extend over a large tract of country, and their position is most advantageous, in the midst of a flat country, within an easy distance of Husavik, a convenient shipping port; and, during the many years they have been closed, the deposits must have very greatly accumulated, and should yield abundantly. Indeed, so strong was this conviction in the minds of the natives that they long opposed the leasing except on very onerous terms, although quite unable themselves to work them.

As these mines are now likely to remain in English hands for many years, a short account of their former history may be read with some interest.

They are situated between 65° 20´ north latitude and the Arctic Sea, or more definitely speaking, lying in the tract between Myvatn on the east, and Jökulsá (glacier river) on the west.

The right of working them was bought from private owners by the Danish king, Frederick the Second, in 1563, and this right has ever since been in the possession of the Danish Crown (now the State). During the reign of this king a considerable quantity of sulphur was extracted, amounting to as much as 400 tons annually. In the reign of his son and successor, Christian the Fourth, the produce appears to have fallen off, and his Majesty was unsuccessful in his endeavours to lease them to foreigners. To the falling-off of their supply of sulphur in this reign, and the consequent scarcity of gunpowder, the Danes attribute their defeat by the Swedes in Holstein (1644).

In 1665 we are informed that the Crown granted a concession for “digging sulphur” to a foreigner, who is stated to have exported large quantities up to the year 1676; since which date no special mention appears to have been made of them until the early part of the eighteenth century, when two foreigners, apparently Germans, acquired in 1724 the right of exporting sulphur from Iceland. They also shipped considerable quantities during the succeeding five years, when the death of the lessees put a stop to this commerce.

After this date, and up to the beginning of the present century, the Danish Government worked the mines for their own account, at times, it appears, with considerable profit, until 1806, when they were again leased to a foreigner. Subsequently, they have at times been worked by private speculators up to 1851, since which date, as already mentioned, they have remained untouched.

In 1840 they were visited by some scientific travellers, who calculated that these northern mines might easily yield an annual net profit of £1000 or £1200. Ten years later they were specially examined by a Danish mineralogist, who discredited this statement, and reported them to be less valuable;[177] but in speaking of the Krisuvik mines in the south, he says, “These might be easily made to yield 200 tons annually,” and yet they have always been considered inferior to the northern mines. A French geologist, Eugène Robert, who visited Iceland in 1835, and afterwards published a treatise on its geology, calls the attention of the Danes to the value of the Myvatn mines, and advises them not to lease them to the Englishmen (who were then applying for them), as the property might become of great consequence in the event of the sulphur mines of Sicily falling off, of which, he affirmed, symptoms had shown themselves.

It will thus be seen that opinions are divided as to the productiveness and present richness of these mines; but so much is certain, that they have for several centuries been worked at intervals with varying results; at times with considerable profit: the history of the country, and the experience of so many years, point to the conclusion that, if properly worked, they would become valuable property.

The mines, for instance, at Reykjahlidar-námar are the richest to be found in all Iceland, and produce large quantities of the purest sulphur.

The reproduction is incessantly going on from upwards of a thousand small eminences, called solfataras, which are found on the ridge along the sides and at the foot of Námarfjall. Rich sulphur deposits are also found at the Ketill Crater (called Fremri-námar), while the least rich are the Krafla-námar, but at all these there is a continual deposition of sulphur going on. They all have the great advantage of lying in the track of one of the few practicable roads in the island, leading to an accessible shipping port.

SECTION IV.

Hôtel de la Ville (Au Troisième), Trieste, 16th February 1873.

The following are the notes which I made, for the use of Mr Lock, upon Mr Vincent’s able and instructive paper.

“Holding sulphur-export to be the most legitimate trade in which Iceland can engage, I rejoice to see the paper by Mr C. W. Vincent, F.C.E.

“The writer’s theory upon the formation of the mineral, by the by, the action of water upon pyrites, is not new, nor am I certain that it is true: perhaps it may be provisionally accepted, until we have a better. He has done good service to students by noticing the similarity of the Icelandic diggings with those of Central Sicily and of the Yellowstone River sources. On the other hand, after actual inspection of the Icelandic sulphur mines, I must differ upon many details with Mr Vincent, who has derived his information from hearsay. He nowhere notices the interesting combination of the Palagonitic groundwork of the island with lavas of modern date, which seems to me a constant feature of these solfataras. The venerable Sir Henry Holland recorded in 1810, that the Krísuvík formation occupied high ground ‘composed principally of the conglomerate or volcanic tufa which has before been noticed:’ this palpable reference to Palagonite has not been worked out as it deserved to be. The ‘vivid word-pictures’ of older travellers are either written in the fine style of former days, or the subjects of description have lost youth and vigour. The ‘tremendous proofs of what is going on beneath us’ are now, or have become, phenomena on a very mild scale; while the ‘thundering noises’ which ‘stunned the ears’ of a former generation, have learned to ‘roar gently,’ and to avoid shaking weak nerves.

“As regards the authorities quoted, I may notice Commander (now Admiral Sir) J. E. Commerell, who in the Vincent lecture appears enthusiastic upon the capabilities of the Krísuvík mines. But that able officer’s more dubious views do not come forth: he expressly states in the same report that ‘a tramway might also be laid down; but, as there are two hills to cross, with other difficulties, I could not positively state whether this were possible or not.’ Mr Seymour (fils) has spent many months in Iceland, but that does not mean Krísuvík. Captain Forbes is also quoted, although it is well known that my friend has not a high opinion of the south-western solfatara, and the sketch of travel over that part of Iceland given in his lively volume (p. 103) suggests anything but facility of transit. When a tramway has to cross a hill-range, and a lava-tract some twelve indirect miles broad, we already expect difficulties. Here, however, I must confess not to have seen the plan and estimates drawn up by Messrs Shields and Gale, who set out for Krísuvík a few days before my departure from Iceland.

“Also Mr Vincent appears to extend the solfatara district of Krísuvík over a space of twenty-five miles, along a fancied volcanic diagonal. This may be the case, but on July 9-10 Mr Chapman and I rode from ‘Krísa’s Bay’ eastward to the Reykir, alias the ‘Little Geysir,’ and, although we looked curiously for the enormous area theoretically assigned to the sulphur formation, we failed to see any sign of it. Our path ran over the normal quaking bogs, over large spills of modern lava poured down the walls of the high interior plateau, and occasionally over a strip of sea-sand. The apparently indispensable Palagonite was also missing till near the end of the second march. Gunnlaugsson’s and Olsen’s large map of Iceland, hereabouts so minute in all its details, does not show a single hot spring between Krísuvík and Reykir; on the contrary, all is coloured red-yellow, as a Hraun (lava-tract). Even the ‘western mine’ of Krísuvík has been described to me by authorities who know the country well, as containing very little sulphur; and a passing visit induces me to believe them.

“All these are minor objections to Mr Vincent’s paper. But when speaking of, or rather alluding to, your concession, he has fallen into grievous error. If he has studied the subject, he simply misrepresents it; if not, he should have avoided all depreciatory notice of the Mý-vatn mines.

“And now for the proofs.

“I read (p. 137) with unpleasant surprise, ‘a violent eruption of the mud-volcano Krabla to a great extent buried the then active strata beneath enormous masses of volcanic mud and ashes, so that the energy has been probably transferred along the line’ (viz., the great volcanic diagonal stretching, or supposed to stretch, from Cape Reykjanes to the Mý-vatn lake) ‘southwards,’ that is to say, to Krísuvík.

“Without dwelling upon the fact that Mr Vincent’s theory about the local production of sulphur renders such ‘transfer of energy’ impossible, I remark that, firstly, the Hlíðarnámar, the nearest deposits of the Mý-vatn sulphur, are at least two miles removed from the extremest influence of Krafla, whilst the Fremrinámar are four times that distance, and the latter are situated upon a much higher plane. To those who have breathed the live sulphur tainting the air for mile after mile, this ‘transfer of energy’ becomes a mere matter of fancy. Secondly, on the very flank of Krafla, the hollow called Great Hell (Helvíti Stærra) shows an abundance of sulphur, which extends right across the valley westwards to Leirhnúkr (mud knoll). In this small section of your concession Gunnlaugsson gives no less than seven Hverar (boiling springs) lying close together. I need hardly pursue this part of the subject: to one who has seen the country the assertion that any eruption from Krafla has effected either the Hlíðar or the Fremri diggings appears inconceivable. Suffice it to say that your six square miles of live sulphur contrast wonderfully well with the two at the south-western end of the island. Krafla alone contains as many solfataras, boiling springs, and ‘makkalubers’ (mud caldrons), as exist in the whole district of Krísuvík, and Krafla is only a part, a very small part also, of the north-eastern deposits.

“Again I see with astonishment (p. 143), that ‘the sulphur at Myvatn, though great in quantity, is at too great a distance from the port of embarkation to permit its extraction being carried on with any chance of competing with that from the Krisuvik mines.’

“It is true that your concession lies some twenty-five direct geographical miles from Húsavík, the nearest available port, whilst those of Krísuvík are only ten distant from Hafnafjörð. But a simple statement of this kind is fallacious, because it conveys the wrong impression. It is known to every Icelander that the northern line is one of the best, the southern one of the worst, if not the worst, in the island. The Húsavík road has the immense advantage of an easy and regular incline from 900 feet high to sea-level, and in the depths of a protracted winter your sledges can always carry down the material dug up during the long summer days. There is nothing to prevent your having your tramway, when such expensive article becomes advisable.

“You are at liberty to make any use you please of these short and hurried notes. Pray understand that my object is by no means to disparage the sulphur mines of Krísuvík; on the contrary, I hope soon to see a company formed, and a stout-hearted attempt made to benefit both the island and ourselves. M. Robert’s opinion upon the capability of Iceland generally to supply an article which every year grows in request, and his truly Gallican horror of the trade falling into English hands, are too well known, and have too often been quoted, to justify repetition. But I can truthfully say, that the Mý-vatn concession will be found preferable to that of Krísuvík, and I regret that Mr Vincent has adopted, without personal acquaintance with Iceland, information which seems to come from suspected sources.

“Why do you not render justice to the Mý-vatn mines by a lecture, with the assistance of maps, plans, and other requisites? Mr Vincent, I see, proposes to continue writing upon the highly interesting sulphur supply of Iceland: pray remember that in these wild solitudes I am wholly dependent upon the piety of my friends and the pity of those who remember me.

“Ever yours truly, “Richard F. Burton, F.R.G.S.

“Alfred G. Lock, Esq.”

SECTION V.

Sulphur in Iceland. By C. Carter Blake, Doc. Sci., Hon. For. Sec. Lond. Anth. Soc. London: E. & F. N. Spon, 48 Charing Cross. 1873.

The fact that sulphur, one of the most useful substances known, and, in the words of Mr Crookes, “the mainstay of present industrial chemistry,” has been an article of commerce throughout all time, and that a ready market has always existed for it, is familiar to all. Like the famous electrum of the ancients, its origin has been comparatively unknown. We shall briefly consider the conditions under which sulphur is found; its geographical distribution over the face of the globe; the method of its preparation for the market, and the circumstances which may lead capitalists to seek for the productive mineral at a shorter distance from our own shores than the Mediterranean or Mexico.

Sulphur is a simple, inflammable, brittle substance, of which all the forms found native belong to the rhombic or trimetric system, and are more or less modified rhombic pyramids. These crystals could not be formed at temperatures approaching that of boiling water, or be exposed to such a temperature without alteration; crystals of native sulphur must therefore have been formed at ordinary temperatures. Sulphur does not occur anywhere in sufficient quantity to constitute a rock, but is widely disseminated throughout rocks of different ages, either implanted in crystals, in small beds, nests and nodules in a pulverulent condition, as a coating, as in some lavas, or as a cement of decomposed trachyte. Dr Sullivan has said:[178]

“In volcanic regions the deposition of sulphur may result from two causes: 1st, the action of oxygen on damp sulphide of hydrogen gas, or on solutions of the gas; and 2d, the mutual decomposition of sulphide of hydrogen, H₂S, and sulphurous anhydride, S₂O. If the former be in excess, water and sulphur appear to be formed; if the latter be in excess, pentathionic acid, H₂S₅O₆, and water are formed; the pentathionic acid is gradually decomposed into sulphur and sulphuric acid, which produce sulphates. In connection with this reaction, it may be observed that several sulphates are associated with the sulphur found in districts where the sulphur is formed from gases escaping through fissures. Old craters having such active fissures called fumaroles, are termed solfaterras.”

So important an influence does the price of sulphur exercise upon the cost of production of bleached and printed cotton stuffs, soap, glass, and other valuable manufactures of this country,[179] that it was the express subject of a commercial treaty, and in 1838 the British Government took very decided steps to put an end to a monopoly attempted to be established in it by the Sicilian Government.

That the present supply of sulphur is inadequate to the demand is proved by its high price, by the use of pyrites as a substitute, and by the inquiries recently made by the British Government as to its existence in Mexico. That the already large demand for this important substance must increase is quite evident when we consider the purposes to which it is applied.

Gunpowder.—Sulphur enters into the composition of this important article in proportions ranging from 10 to 20 per cent., according to whether the powder is required for war, sporting, or blasting purposes.[180] When we consider the vast quantity required by the gigantic armaments now maintained in every civilised country, as well as by the numerous mining and engineering operations at present in existence throughout the world (in which it is indispensable for blasting), we can form some idea of the immense amount of sulphur annually consumed in the manufacture of gunpowder alone.

Sulphuric Acid.—One of the most important chemical agents required in the arts and manufactures, is used very extensively for making soda-ash for bleaching linen, woollens, etc., straw, etc.,[181] manure making, and for a variety of chemical productions; also for refining metals.[182]

Soda-ash (alkali) is obtained from common salt by means of concentrated sulphuric acid. It is used instead of barilla for soap-making, as a substitute for pot and pearl ashes in glass-making; for cleaning and bleaching; and, in the form of carbonate, for medicinal and domestic purposes. In the year 1862 the enormous quantity of from 100,000 to 120,000 tons of the former, and from 25,000 to 30,000 tons of the latter, was made in Great Britain alone.[183] That quantity is now vastly increased.[184]

Manures.—A great consumption of sulphuric acid has of late years taken place for agricultural purposes,[185] viz., in the preparation of superphosphate of lime, the most active manure for turnips, grass, and cereals.

Oïdium.—Within the last few years it has been discovered that the use of flowers of sulphur, containing traces of sulphuric and sulphurous acid, and of carburetted hydrogen, is a protection against the vine disease—oïdium. Although no reliable information exists as to the exact quantity used for this purpose, yet it is known to be very considerable.

Flowers of sulphur have recently been strongly recommended as a remedy for the potato disease.[186]

Such are a few of the principal objects to which sulphur is devoted, and for which it is needed; thereby proving most conclusively that THE CONSUMPTION IS ONLY LIMITED BY THE SUPPLY.

Sulphur is found in Corfu, the neighbourhood of Rome, Transylvania, Spain, the clear or borax lake in California, the slopes of the Popocatepetl, in the province of Puebla, Mexico; in Montana, North America, and in the Andaman and the Japanese islands. Supply from these sources is practically impossible, and the whole supply of sulphur to Europe and America is derived from the Sicilian sulphur-deposits, the imports of which into this country arose from 16,686 tons in 1842 to 58,204 tons in 1859,[187] and over 75,000 tons in 1862;[188] and in France, from 6668 tons in 1820 to 33,361 tons in 1855.

Sulphur is found either (a) in a pure native state, (b) as gas, or (c) in mechanical admixtures with clays or other earths. The method of extraction of sulphur when mechanically combined with foreign substances is thus described in Richardson and Watts’ “Chemical Technology,” vol. i., part iii, p. 314:

“It has already been noticed that the deposits of sulphur are always associated with various mineral or earthy matters, and three processes are followed to separate the principal part of these impurities, which generally amount to more than one-half of the entire weight of the deposit.

“When the deposit is rich in sulphur it is melted in a cast-iron pot, heated by an open fire. The melted mass is stirred with an iron rake to facilitate the separation of the earthy matters, which are allowed to fall to the bottom. The liquid sulphur is then removed by a ladle, thrown into an iron vessel, and allowed to solidify. The temperature ought to vary between 250° and 300° Fahr., and never reach 480°, at which point the sulphur would take fire. The residue which remains, and contains more or less sulphur, is removed, and may be treated by either of the following plans:

“A small blast furnace, constructed of fire-brick or stone, is charged with the sulphur-stone at the bottom, which is ignited, and fresh charges of the sulphur-stone are thrown in from time to time. The working holes at the sides admit a small supply of air to support combustion on the surface, by which means sufficient heat is generated to melt the sulphur, which runs off at the bottom through a pipe into an iron pot, where it solidifies.

“The third plan is suitable for treating the impure sulphur-stone, containing from 8 to 12 per cent, of sulphur. It consists of a furnace sufficiently wide to receive two rows of earthen pots—the vessels for distillation—which are arranged in pairs somewhat raised above the sole of the furnace, upon the supports so that the necks of the pots are a little above the top of the furnace. Thus the mouths of the pots are free, and having been charged from without, they are closed by the lids, cemented on, and the distillation begins. The sulphur vapours pass over by the lateral tubes to the receivers, where they condense to liquid sulphur, which flows through into a vessel filled with water, and there solidifies.”

We have indicated the three conditions under which sulphur is found. The sulphur in a gaseous state in Iceland, where, besides the large and rapid deposit of the sulphur in and upon the ground, an immense quantity escapes in the sulphureous vapour, is now entirely wasted, but with the adoption of the improved Mexican process an enormous saving would result. Now the whole of this may be recovered by condensing these vapours in clay vessels, a method practised with great success in Mexico, where in certain places the fumes escape from the soil and can be utilised only in this manner. The sulphur thus obtained is required at the mint of the city of Mexico and at the assaying works.

Sulphur is an essential product of volcanic action: now Iceland is par excellence the spot of the world where volcanic action is at its maximum, and Iceland, as a consequence, is the spot where sulphur is found most extensively. The districts round the active volcanoes of Etna, in Sicily, and Vesuvius, near Naples, supply the whole amount of sulphur now used. In seeking, then, for a new source of this commodity, we should naturally turn our attention to a volcanic district. And where in the whole world does there exist another country so pre-eminently volcanic as Iceland? Its fearful lava-tracts, its vast plains of scoriæ, volcanic dust and ashes, its pools of boiling water, its spouting geysirs, its vast caldrons of seething mud, proclaim its volcanic origin. It owes its upheaval wholly to volcanic agency, and is composed almost entirely of igneous rocks.

While these pages are passing through the press, the volcanic force has broken out in Iceland, and Skaptar Jökull burst into eruption for four days in the month of January last.

The wildest theories have been uttered respecting the modes of origin of sulphur. An inquirer, who investigated the southern Icelandic mines in a superficial manner, has thrown out a theory that the sulphur derived from Krísuvík, and other southern localities, has been produced by the action of water on the sulphurets of iron contained in the rocks. This idea, which rivalled some of the speculations of De Luc, was expressed by him in a paper read before the Society of Arts, on the 15th January 1873. The notion was, that the hidden fires of Iceland dwell in the crust of the earth, and not in its interior; that the boiling springs and mud-caldrons certainly do not derive their heat from the depths of our globe, but that the fire which nourishes them is to be found frequently at only a few feet below the surface, in fermenting matters which are deposited in certain strata! How far this theory is probable may be estimated when we glance at the converse hypothesis, which we must impress upon our readers. The lava at Myvatn is only a few feet, or at most, a few yards, thick; this is clearly shown by the fact that the gaseous vapour escapes from innumerable holes in the lava lying between the mines and the lake. The stoppage of an outlet for the upward flow of the gas has caused the outbreak of the fluid at spots far distant from the original central “crater” of the sulphur volcano. The geology of Mr Vincent is decidedly vague.

That a great volcanic diagonal line stretches from Cape Reykjanes to the lake of Myvatn, is a theory which is unproven by topographical science, and which a glance at the map, which shows the elevated hills of Lángjökull, Hofsjökull, and Vatnajökull extending across this imaginary line, is sufficient to disprove. The relative elevations of the mountains, from Snæfell on the east, to Eyjafjallajökull on the west, seem to indicate that the central line of volcanic action has been along a line parallel with the south-south-east coast, and which has left the formations in the neighbourhood of Lake Myvatn, with the small volcanic chain of Sellandafjall, Bláfjall, Hvannfell, and Búrfell, entirely to the north. The abrupt escarpment of the greater chain lies along its south-eastern strike, and the fissures along which the parallel rivers from the Jökuldalr to the Hrútafjörðará flow are, according to a well-known geological law, produced on the less inclined slopes. Whilst Mr Vincent’s theoretical geology verges on the speculative, his assertion of known geographical facts is inexact.

In 1857, when the temporary cessation of war by England led the British Government to look for fresh sources of gunpowder supply for Europe, Captain J. E. Commerell, of H.M.S. “Snake,” was sent to Iceland by the Lords Commissioners of the Admiralty to report upon the capabilities of the mines of Krísuvík and Húsavik. He found the Krísuvík mines, though comparatively close to the sea, did not possess a safe port of debarkation nearer than Hafnarfjörðr. An ex parte statement of the “objects, pleasures, and advantages” of the “truly eligible” Krísuvík sulphur mines leaves itself open to severe criticism, and the opinion of Commander Commerell that “the sulphur at Myvatn, though great in quantity, is at too great a distance from a port of embarkation to permit its extraction being carried on with any chance of competing with that from the Krísuvík mines,” may be profitably contrasted with that of A. de Capel Crowe, Esq., H.B.M.’s Consul in Copenhagen.[189]

Consul Crowe’s remarks as to the richness of these deposits are corroborated by Commander Commerell himself, who says in his report:

“I found at Námarfiall, which lies about six miles to the east of Lake Myvatn, large beds of sulphur in a very pure state; and though the quantities already deposited were very great, no signs appeared of their having been worked.”

We shall give the testimony of a few of the more distinguished Icelandic travellers relating to the value of the Myvatn fields. But quotations are only made from authors whose scientific and literary position render their opinion of value and authority.

The testimony of the Rev. Mr Henderson, the celebrated missionary in Iceland, cites the following notorious and well-known facts:

“To the east of Krabla the sulphur mines of Reykjahlid.[190]

“Of the sulphur mountains a particular description is given in the journal.[191]

“...Several huge dark mountains that are again relieved in the east by the Námar, or sulphur mountains, from the decomposition going forward, in which a vast profusion of smoke is constantly forming, ascending to a great height in the atmosphere.[192]

“Olafsen and Povelsen, describing two pools on the south-east side of Krabla, say that the whole region completely answers to the well-known solfatara in Italy.”[193]

Describing the neighbourhood of Myvatn, he, in an eloquent description, says:

“On either side lay vast beds of sulphur covered with a thin crust, containing innumerable small holes, through which the vapour was making its escape. In many parts the crust, which presented the most beautiful aluminous efflorescence, was not more than half-an-inch in thickness; and on its being removed, a thick bed of pure sulphur appeared, through which the steam issued with a hissing noise. The sublimation of the sulphur is produced by the constant ascension of this vapour; and it is found to possess greater and less degrees of purity, in proportion as the soil is more or less porous. In general, however, these mines are VASTLY superior to any other in Iceland, owing to the intense degree of subterranean heat, and the very loose and porous nature of the earth at this place.

“The sulphur mountain rises to a considerable height from the east side of the hollow in which these mines are situate. It does not exceed a mile in breadth, but is more than five miles in length, stretching from the east end of the lake in a northerly direction, between the volcanoes Krabla and Leirhnukr, where it joins the ridge by which these two mountains are connected. The surface is very uneven, consisting of immense banks of red bolus and sulphur, the crust of which is variegated with random mixtures of yellow, light-blue, and white colours, and in some places a soft sandstone makes its appearance through the predominant mould. I could also observe holes, out of which the sulphur has been dug by the peasants.

“The jetting is accompanied with a harsh roar, and the escape of a vast quantity of vapour strongly impregnated with sulphur.... Passing a desolate farm, and keeping at a distance from the sulphur banks, which appeared in the face of a contiguous mountain, we succeeded in reaching the base of Krabla.... On the northern margin rose a bank, consisting of red bolus and sulphur, from which, as the wind blew from the same quarter, we had a fine view of the whole. Nearly about the centre of the pool is the aperture whence the vast body of water, sulphur, and bluish-black bolus is thrown up; and which is equal in diameter to the column of water ejected by the Great Geyser at its strongest eruptions.... What was visible of Krabla appeared covered with the same clay, pumice, and sand as that on which I stood, only diversified by beds of yellow sulphur.... To the west of this wilderness lay a number of low mountains, where the Fremri Námar are situated. Directly in front was the valley filled with lava above described; near the farther end of which the large columns of smoke ascending from the sulphur springs had a fine effect.”[194]

The Rev. S. Baring-Gould, whose researches into Icelandic literature have been of such service to the philologist, gives the following description of the view from the slope above Reykjahlíð, looking across the Lake Myvatn:

“You see the indigo chain of Blafell, beyond which is a field of sulphur and boiling mud called Fremri-Námar, not visited by travellers, as it is difficult of access, and inferior in interest to the Námarfjall springs.... (From Námarfjall) in half an hour we reach the sulphur mountains, a chain of red hills, perfectly destitute of vegetation. We dip into a glen, and find it full of fumaroles, from which steam is puffing, and sulphur is being deposited. These run along the dale in a zigzag. By the road-side I noticed a block of pure sulphur, from which every traveller breaks a piece, so that in time it will disappear altogether.

“Passing through the Námar-skarth, a winding cleft in the mountains, I came upon a plain of mud, the wash from the hills bounded by a lava-field; the mountains steaming to their very tops, and depositing sulphur, the primrose hue of which gives extraordinary brightness to the landscape.... Presently the beautiful Lake Myvatn, or Midge Lake, opened before us, studded with countless lava islets; beyond was the sulphur range, yellow as though the sun ever shone on it.”[195]

In Mr Shepherd’s work on the North-West Peninsula of Iceland, we find another lucid description:

“We rode to the sulphur mountains on the east of the lake (Myvatn). These large hills are a very wonderful sight. They are of various colours, a variety of mixtures of red and yellow. From their sides are emitted various jets of steam, and masses of bright yellow sulphur are strewed all around them.... All around the soil was very treacherous, consisting of hot mud, with a covering of sulphur about an inch in thickness, which in most cases was sufficiently strong to bear a man’s weight. When the crust was broken, steam issued forth, strongly impregnated with sulphur.”[196]

The distinguished Lord Dufferin (the present Governor-General of Canada) in his charming book, “Letters from High Latitudes,” says:

“Opal, calcedony, amethyst, malachite, obsidian, agate, and felspar are the principal minerals; OF SULPHUR THE SUPPLY IS INEXHAUSTIBLE.”

M’Culloch’s “Geographical Dictionary,” vol. i., p. 585, under the heading “Iceland,” says:

“Few metals are met with. Iron and copper have been found, but the mines are not wrought. The supply of sulphur is inexhaustible; large mountains are encrusted with this substance, which, when removed, is again formed in crystals by the agency of the hot steam from below. Large quantities were formerly shipped; but latterly the supplies sent to the foreign market were comparatively small.”

“Chambers’s Encyclopædia,” under the heading “Iceland,” vol. v., p. 505, says:

“The mineral wealth of Iceland has only begun to be developed. In no part of the world is sulphur found in such abundance.”

An adequate idea of the value of the Icelandic sulphur fields, as compared with those of Italy, cannot be conveyed by the reports of travellers. To thoroughly comprehend this, we must bear in mind the reproductive properties displayed by solfataras, and the best means suggested by practice to extract the sulphur and yet not interfere with this peculiarity.

The process for the separation of the sulphur at the celebrated solfatara of Pozzuoli, near Naples, where the sulphur is condensed in considerable quantities amongst the gravel collected in the circle which forms the interior of the crater, is conducted as follows: The mixture of sulphur and gravel is dug up and submitted to distillation to extract the sulphur, and the gravel is returned to its original place, and in the course of about THIRTY years is again so rich in sulphur, as to serve for the same process again.[197]

We thus see that the reproductive process occupies a period of THIRTY years in the Italian mines, whereas the same results are produced in THREE years in the Icelandic mines, i.e., that a given area in Iceland will produce ten times the quantity of sulphur, or is ten times as valuable, as the same area in Italy.

“The permanency of the volcano, as a source of sulphur, would depend on the rapidity with which the sulphur would be replaced, after the sand had been once exhausted. The time required for this is not necessarily fixed to periods of twenty-five or thirty years. In Iceland, at a similar spot the sulphur is renewed every two or three years.”[198]

The nearest port suitable for shipment of the sulphur is “Húsavík,” situate in the Bay of Skjálfandi; it is perfectly accessible at all times of the year. Mr Consul Crowe having been questioned on the subject, states[199] that:

“The Icelandic ports are, owing to the influence of the Gulf Stream, in ordinary years accessible to shipping all the year round, and shipments can safely be made during seven months at ordinary rates of freight and insurance. Húsavík, as a rule, is never frozen up, the only impediment to free navigation being the floating ice which at certain seasons is loosened from Greenland, and may for a time lie off the coast. Such occurrences, however, have their stated times and seasons, which are well known to navigators in those waters; in some years there are no hindrances of the kind at all, and shipments in good vessels may be made all the year round. In support of this statement, I may mention the fact that steamers leave Copenhagen for Iceland as late as the middle or end of October, and would do so later were there sufficient goods or passengers to make them pay. Again, the Iceland ‘Althing’ have recently proposed to raise funds for running steamers round the island ‘all the year,’ and thus supply the want of internal communication; and, if the proposal fell through, it was only on financial grounds, and not from inaccessibility of ports from ice. I am therefore simply repeating facts in stating that, as a rule, Iceland navigation is free all the year round. The island is but a two days’ journey from Scotland, and with suitable vessels an almost uninterrupted intercourse might, in ordinary seasons, be kept up. In further confirmation of what I have stated, I may add that this same warm current from the Mexican Gulf, which is so beneficial to Iceland, keeps also all the Norway ports, from the Naze to the North Cape, ice-free all the year round.”

The road from Hafnarfjörðr to Krísuvík will certainly be improved by the formation of a railway.

It has been said by Professor Paijkull that this road is one of seven or eight hours’ journey.

“This road is one of the best in Iceland. The ‘heiði’ south of Húsavik is free from stones, and is level, although only sparsely overgrown with grass. Neither are there any hills or fjelds to be met with along it, and there are only a few small streams to be crossed. The last few miles north of Myvatn certainly consist of a sandy plain, but it is tolerably level, and the road is pretty good, owing, I suppose, to the sulphur traffic from the solfataras, near Myvatn, to Húsavik, in former days, in which 100 horses are said to have been employed at one time.”[200]

In 1868, the late foreign minister of the United States, Mr W. H. Seward, one of the most far-sighted statesmen which that country has ever produced, was able to anticipate the future importance of the Iceland sulphur mines both to Europe and to America. It was even proposed that the United States Government should purchase both Iceland and Greenland, as well as St Thomas, from the Danish Government. To promote this object, Mr B. M. Pierce was sent to Iceland to report on the mines. Extracts from his report are subjoined:

“The sulphur mountains, beds, and mines are very rich and extensive, easily worked, and of immense value. The sulphur is supplied at half the cost of that furnished by the Sicilian mines, which it is believed will soon be exhausted. The possession of these mines as a part of our territory is a question of vital magnitude.

“...By the way of Reykjahlid and Krabla, where are the most extensive sulphur deposits of the island.

“There are two principal fields of sulphur in Iceland; one near Krabla and Reykjahlid in the north-eastern, the other at Krísuvík in the south-western corner. The former is by far the most extensive region, but the latter gives the purer product. Every traveller gives us a description, more or less minute, of these sulphur hills, and the beds of pure yellow, often a foot thick, which extend about them. Up to a few years ago the sulphur had only been explored in the rudest way by the natives. The industry thus carried on was almost insignificant in result, and was soon abandoned when the supply of surface material became scanty. Still the exportation of sulphur was enough during the days of the peasant mining to give the brightest hopes of what it would be under enlightened management and economy. One of the most interesting and remarkable facts connected with these mines is that a region apparently exhausted becomes re-sulphurised again, so that the stores of brimstone are PRACTICALLY as INEXHAUSTIBLE as those of the infernal regions. Although the mines of Krísuvík are twenty miles from Hafnarfjörðr, one of the best harbours in the island, and those of Krabla are farther still from the seaboard, and from the principal trading station of Húsavik, it would appear that pure Icelandic sulphur is excessively cheap, half the price, say some, of Sicilian sulphur. With improved means of transportation it would control the market. The Oxonian, remarking on this, says (p. 138), ‘like everything else in Iceland, the light is under a bushel.’ Our most trustworthy information comes from Forbes, who, being an officer, sees the importance of the sulphur supply, and enters energetically into a thorough discussion on the prospects of the Iceland beds. We shall give the substance of what he says: ‘The deposits are formed by the decomposition of the sulphurous fumes that burst up from the ground, and afterwards sublimate as solid sulphur. A part is mixed with clay; a part is almost pure sulphur, containing but 4 per cent. of gangue. The number and energy of these sulphur gases continually coming up is incredible. The sulphur earth, or impregnated clay, averages from 6 feet to 3 feet in thickness, and contains 50 or 60 per cent. of pure sulphur.’

“Sulphur is found also at Námafjall, in the north of Iceland, in geological circumstances analogous to those of the beds at Krísuvík. It is found there generally in concrete masses of a citron-yellow colour, quite pure, sometimes very plentiful, and generally associated with lime and silica. It is to be regretted that the Danish Government does not favour this industry, which would furnish as fine sulphur as that of Sicily, and doubtless at a lower price. Besides, Denmark possesses in Iceland immense stores, which will one day be of great value to her when those of Sicily are exhausted.”

Before the concession was granted to Mr Lock, Professor Johnstrüp was sent by the Danish Government to survey and make plans of the mines. His report is inserted at length:

“Referring to the consul’s request to me in date of the 27th of last month, I beg to inform him that on the journey which I made last year to Iceland I visited the sulphur mines belonging to the State there, which lie to the east of Myvatn, and I made maps of them, which were sent to the Minister of Justice, who will, no doubt, let you have copies of them. From these you will be able to see that the richest mines are to be found in that part called Reykjahlidar-Námar, where large deposits of the purest sulphur are to be found.

“The reproduction is incessantly going on from about a thousand small eminences (solfataras), which are found on the ridge, along the sides, and at the foot of Námarfjall.

“Further rich sulphur mines are to be found at the Kétill crater, called the Fremri-Námar, while the least rich mines are the so-called Krabla-Námar, but also at these there is a continual production of sulphur going on. The first-mentioned mines are the richest to be found in the whole of Iceland, and have the advantage of lying in the track of a PRACTICABLE ROAD to the shipping port of Húsavik, which road is among the best in the island. As regards the position of the mines, I must refer you to Olsen and Gunnlaugsson’s map of Iceland, on which they are marked. It will be a pleasure to me should these particulars be of service to you.

“(Signed) J. F. Johnstrüp, “Prof. Mineralogy at the Copenhagen University.

“April 30, 1872.”

The examination of these facts is quite enough to show the inquirer that the transit from Myvatn to Húsavík is more practical, and of more easy access, than that from Krísuvík to any of the ports at the south-west corner of the island, which have been extolled by Mr Vincent in his ex parte glorification of the Krísuvík mines. We will now turn to the testimony of a far greater traveller, whose opinion on the subject ought, indeed, to be regarded as final. Captain R. F. Burton, in his recent exploration of Iceland, devoted much time to the examination of the Myvatn sulphur deposits. The great question is answered by him in the following letter which appeared in the London Standard, Nov. 1, 1872:

“Sir,—Perhaps you will allow me, in continuation of my letter of October the 14th, to attack the subject of the sulphur deposits in Iceland now belonging to British subjects.

“For many years these diggings, so valuable since the exhaustion of the supply from Sicily, were a bone of contention between France and England....

“Denmark can hardly work the mines for herself without a great expenditure of capital, which will find its way into Icelandic pockets, and thus she wisely leases her property to strangers. She relies upon the fact that sulphur has risen from £4, 10s. to £7 per ton, and consequently that her Iceland diggings must become more valuable every year.

“I spent three days—from August 7th to August 9th, 1872—at the solfataras of Mý-vatn, or Midge Lake, situated to the north-east of the island. I lodged at the farm of Reykjahlið (reeky ledge), under the roof of the well-known Hr Pètur Jónsson, whose alacrity in composing a bill of charges has won for him a wide reputation.

“On Wednesday, August 7th, I set out under the guidance of this worthy to inspect the diggings of Krafla, generally but erroneously written Krabla. And now a verbatim extract from my diary will assure the reader that my statements are completely free from the process called ‘cooking.’

“Rode to Leirhnúkr (mud knoll) in one hour fifteen minutes. At once understood an emplacement very imperfectly described by old travellers. It is the northern head of a spine, a sharp prism about one mile broad, with a magnetic direction of 215 deg., in fact, nearly due north—south. It is a mass of Palagonite (sea-sand forming a stone), everywhere capped by spills and gushes of modern lava, and sulphur abounds at the junction of these formations. The hillock of Leirhnúkr is one vast mass of sulphurous deposits. I counted seven wells upon the slope, whilst the lowlands around were spotted with unwholesome-looking eruptions. Rode east to Helvíti, which the Rev. Mr Henderson described in 1815 as a crater, not unworthy of its grim name. ‘Hell,’ here as elsewhere, has been ‘dismissed with costs,’ the placid blue lake, ruffled at times by the passing breeze, and blowing off odours the reverse of Sabæan, is now hardly worth visiting. At Hrafntinnuhryggr (raven stone ridge)—excuse the word, I did not make it—expected to find, as the ‘Obsidian Mountain’ has been described, ‘a heap of broken wine bottles shining with their jet-like colouring.’ Found nothing of the kind, but picked up some decent specimens. Rode back much edified, etc., etc....

“On the next day rode to the Fremrinámar (outer warm-springs) to the south with some easting to Reykjahlíð. Found the road utterly dissimilar to anything laid down in maps. After four hours thirty minutes of rough travelling, reached the deposit which has been worked for some generations, but which cannot be said to have been EVEN SCRATCHED. The ‘lay’ is upon the north-eastern, the eastern, and the southern flank of a crater, described by the late Professor Paijkull as ‘probably the largest in Iceland.’ Immense deposits covered the ground, and white fumes everywhere filled the air. Whole torrents of what Mr Crookes calls the ‘mainstay of our present industrial chemistry’—I mean sulphur—have here been ejected. Could not count the hissing ‘hot coppers,’ popularly called fumaroles. Returned after a stiff ride of eight hours thirty minutes, which gave a fine view of the Ódáða Hraun, the ‘great and terrible wilderness’ of lava to the south-west, etc....

“August 9th was a lazy day, spent in preparing for a trip to the desert. Inspected the Hlíðarnámar (ledge springs), from which the farm of Reykjahlíð takes its name. Bravely objected to be deterred by the ‘smell of rotten eggs,’ by the ‘suffocating fumes,’ and by the chance of being ‘snatched from yawning abysses by the guide’s stalwart arms.’ Perhaps the conviction that the abyss nowhere exceeds three feet in depth may account for my exceptional calmness in such deadly peril. The Hlíðarnámar, or Ledge Springs, lie west of the sulphur mountain, and on a lower plane than the eastern deposits. They are bounded north by two lava-streams issuing from the base of the Hlíðarfjall, and south by independent outbreaks of lava, showing hosts of small detached craters. East is the hill, and west the Mý-vatn water, and its selvage of fire-stone. The area of this fragment of the grand solfatara may be one square mile.

“The spade deftly wielded threw up in many places pure flowers of sulphur. According to Dr Augustus Vöelcker, this bright yellow matter gives 95·68 per cent., and according to the Icelandic traveller Ólafsson, it is readily renewed. Below the golden colour usually is a white layer, soft, acid, and mixed with alum; it is calculated to yield 20 to 30 per cent. Under it again are the red, the dark purple, the chocolate, and other tints, produced either by molecular change in the mineral, or by oxygen which the sulphur no longer modifies. Here the material is heavy and viscid, clogging the spade, and the yield is reported at 50 to 60 per cent. These figures will show the absolute value of the supply. Beneath, at short distances, say at three feet, lies the ground-rock, invariably Palagonite: thus ‘falling in’ merely means dirtying the boots. Between the yellow outcrops stretch gravelly tracts which the spade showed to be as rich as the more specious appearances. Many of the issues are alive, and the dead vents are easily resuscitated by shallow boring, in places even by pulling away the altered lava-blocks which cumber the surface.

“Leaving my horse in a patch of the wild oats that everywhere characterise this region, I walked up the sulphur mountain, whose white and yellow washings, so conspicuous from afar, prove to be sulphur, stones, and sand deposited by the rain upon the red clay. Here we picked up crystals of alum and lime and fragments of gypsum and selenite. The crests and box-shaped masses of Palagonite and altered lava gave fine views of the lowlands. On the summit we found some small mud-springs, which Iceland travellers have agreed to call by the corrupted name ‘Makkaluber;’ the people know them as ‘Hverar.’ This peculiarity is therefore not confined, as writers assert, to the eastern hill feet. The richest diggings lie below the crest, and here the fumes escape with a fizz and a mild growl, which vivid fancy has converted into a ‘roar.’ I returned from the immense soufrière vastly edified with the spectacle of so much wealth lying dormant in these days of capital activised by labour, etc., etc....

“To the question, ‘Will this sulphur pay its transport?’ I reply unhesitatingly, Yes, if great care and moderate capital be expended upon the mines. In the first place, the live vents which waste their sourness on the desert air must be walled round with stones, or, better still, with planks, and the fumes should be arrested, as in Mexico, by pans and other contrivances. The working season would be the summer, AND THE QUANTITY IS SO GREAT THAT MANY SUMMERS MUST ELAPSE BEFORE THE THOUSANDS OF TONS WHICH COMPOSE EACH SEPARATE PATCH CAN BE CLEARED OFF. In winter the produce can be sent down to Húsavík (House’s Bay), by sledges, not the Esquimaux-like affair at present used in Eastern Iceland, but the best Norwegian or Canadian. The road is reported by all travellers to be exceptionally good, running for the most part over gently undulating heaths, overlying basalt. There are no rivers of importance on the way, and the fall is about 1500 feet in forty-five English statute miles. The line is wrongly placed in Gunnlaugsson’s map: it runs on the eastern, not the western shore of the Langavatn, and it passes to the east of the celebrated Uxahver. I am also assured that the much-abused Bay of Húsavík is a safe harbour, when proper moorings are laid down, that no vessel has been lost there during the last thirty years, and that Captain Thrupp, of H.M.S. ‘Valorous,’ judged favourably of it. This also was the verdict of an old Danish skipper, who assured us that during the last twenty-five years he has been trading between Copenhagen, Hull, and Húsavík, reaching the latter place about the end of February, and making his last voyage home in October. During the ‘balance’ of the year masses of floe-ice prevent navigation.

“From such a speculation present returns may be expected. When income justifies the outlay a tramway would greatly cheapen transit. The ships which export the sulphur can import coal, and now that the officinal treatment of sulphur has been so much simplified by the abolition of train-oil, nothing else except pressed hay for the cattle is wanted. When one patch is exhausted, the road can be pushed forward to another. I am persuaded that the whole range, wherever Palagonite and lava meet, will be found to yield more or less sulphur. Of course it will be advisable to purchase sundry of the farms, and these, in Iceland, range in value from £300 to £800 maximum. The vast waste lands to the east will carry sheep sufficient for any number of hands; and good stone houses will enable the Englishman to weather a winter at which the Icelander, in his wretched shanty of peat and boarding, looks with apprehension. I have already spoken about the excellence of the summer climate, and any gazetteer shows that the change of temperature at Montreal is more to be feared than in Iceland.

“I am, &c., “Richard F. Burton.

“Athenæum, “October 16, 1872.”

The very language of Iceland seems to indicate the importance of its sulphur deposit. It is a significant fact that the Icelandic language indicates sulphur as the “burning-stone,” Brennisteinn, unlike the Danish Svovel, which is obviously derived from Sulphur, Lat.

Mr Vincent’s theory that sulphur is produced by the action of water on pyrites, though having some elements of probability in it, is nevertheless entirely unproven in the present state of science, and it is most unfortunate that throughout his paper, theory and fact are mingled in equal proportions, each being independent of the other. “Tant pis pour les faits.”