FEBRUARY. (continued 3)

It is observed by Dr. Bancroft, that when lamp black has been incorporated with common ink, by first rubbing the former in a mortar with a mucilage of gum arabic, the writing done with it could not be rendered invisible by the application of muriatic acid; and, doubtless, such an addition of lamp black would hinder the letters from ever becoming illegible by age, at least within any length of time which the paper and parchment could be expected to last. But ink made with this addition would require to be frequently shaken or stirred, as the lamp black would otherwise be apt to separate and subside.

In the making of indelible ink, the receipt for lamp black before given may be of considerable importance.

Calico Printing.

Perhaps no object has more engaged “the ingenious chemist’s art” than this, and leave is craved to conclude this diversion from the mayoralty seal of London, by what may be serviceable to some who are actively engaged in an extensive branch, from whence our private chambers, and the dresses of our wives and daughters, derive continual improvement.

Prosubstantive, or Chemical Black, for Calico Printers.

“Some years ago,” says Dr. Bancroft, “I purchased of a calico printer, possessing great knowledge of the principles and practice of his art, the secret of a composition which he had employed with success, as a prosubstantive black, and which, as far as I can judge from experiments upon a small scale, deserved the high commendations which he bestowed upon it: and though I have never obtained the smallest pecuniary advantage from this purchase, in any way, I will here give the full benefit of it to the public. The following was his recipe, with some abbreviations of language: viz. Take two pounds of the best mixed galls, in powder, and boil them in one gallon of vinegar, until their soluble part is extracted, or dissolved; then strain off the clear decoction, and add to the residuum of the galls as much water as will be equal to the vinegar evaporated in boiling; stir them a little, and after allowing the powdered galls time to subside, strain off the clear liquor, and mix it with the former decoction, adding to the mixture six ounces of sulphate of iron; and this being dissolved, put to it six ounces more of sulphate of iron, after it has been previously mixed with, and dissolved by, half of its weight of single aquafortis; let this be stirred, and equally dispersed through the mixture, which is to be thickened by dissolving therein a sufficient quantity of gum tragacanth, (of which a very small proportion will suffice.) Calico, after being printed or pencilled with this mixture, should, when the latter is sufficiently dried, be washed in lime water, to remove the gum and superfluous colour, and then either streamed or well rinsed in clear water. This composition has not been found to weaken, or injure, the texture of calico printed or pencilled with it, and the colour is thought unobjectionable in regard to its blackness and durability.”

It is added by Dr. Bancroft, that “when sulphate of iron is mixed with aquafortis, the latter undergoes a decomposition; the oxygen of the nitric acid combining with the iron, and raising it to a much higher degree of oxidation; the result of these operations is the production of a fluid which has the consistence and smooth appearance of oil, and which (though the name may not be quite unexceptionable) I will call a nitro-sulphate of iron. I have been induced to believe, from several trials, that a better prosubstantive black than any other within my knowledge may be formed, by taking a decoction, containing in each gallon the soluble matter of two pounds of the best galls, in sorts, and when cold, adding to it for each gallon twelve ounces of sulphate of iron, which had been previously mixed with half its weight of single aquafortis, (of which one wine pint should weigh about twenty ounces,) and, by the decomposition just described, converted to the nitro-sulphate of iron just mentioned. By thus employing twelve ounces of sulphate of iron, oxygenated by nitric acid, instead of six ounces of the latter, with six ounces of the green sulphate in its ordinary state, an improvement in the colour seems, by my experiments, to have been invariably produced, and without any corroding or hurtful action upon the fibres of the cotton.”

With these scientific receipts and suggestions it may be agreeable to close. Matters of this kind have not been before introduced, nor is it purposed to repeat them; and those who think they are out of place at present, may be asked to recollect whether any of themselves ever obtained knowledge of any kind that, at some period or other, did not come into use?

NATURALISTS’ CALENDAR.

Mean Temperature 40·72.

February 27.

CHRONOLOGY.

A Scotch newspaper of the 27th of February, 1753, relates, that on the preceding Wednesday se’nnight, the river Tweed was dried up from six o’clock in the morning to six in the evening, the current having been entirely suspended. On the 20th of February, 1748, the river Sark, near Philipston, in the parish of Kirk Andrews upon Eske, and the Liddel, near Penton, in the same parish, were both dry. At the same time other rivers also lost their waters. These remarkable phenomena are naturally accounted for in the “Gentleman’s Magazine for 1753,” vol. xxiii. p. 156.

NATURALISTS’ CALENDAR.

Mean Temperature 41·39.

February 28.

Dr. Johnson.

It was recorded in the daily journals, on the 28th of February, 1755, that “the university of Oxford, in full convocation, unanimously conferred the degree of master of arts on the learned Mr. Samuel Johnson, author of the New English Dictionary.” Such a testimony to distinguished merit, from a learned university, was, perhaps, such a reward as Dr. Johnson appreciated more highly than others of more seeming worth; the publicity given to it at the time is evidence of the notoriety he had attained by his literary labours, and of the interest taken in his fame by every class of society. He taught and admonished all ranks, in a style that charmed by its luxuriant amplification of simple truths, when the majority of people refused the wholesome labour of reflection. Johnson’s ethical writings verify the remark of a shrewd writer, that “a maxim is like an ingot of gold, which you may draw out to any length you please.”

Gin Lane.

The “Historical Chronicle” of the “Gentleman’s Magazine,” notices that on this day, in the year 1736, a proposal was submitted to the house of commons “for laying such a duty on distilled spirituous liquors as might prevent the ill consequences of the poorer sort drinking them to excess,” whereon it takes occasion to adduce the following fact: “We have observed some signs, where such liquors are retailed, with the following inscriptions, Drunk for a penny, dead drunk for twopence, clean straw for nothing.” This record establishes the reality of the inscription in Hogarth’s fearful print of “Gin-lane,” and marks a trait in the manners of that period, which, to the credit of the industrious classes of society, has greatly abated.

Drunkenness exists nowhere but in the vicious or the irresolute. “Give a poor man work and you will make him rich.” Give a drunkard work and he will only keep sober till he has earned enough to drink again and get poor. While he is drinking he robs himself of his time; drinking robs him of his understanding and health; when he is unfit or disinclined to work he will lie to avoid it; and if he succeeds in deceiving, he will probably turn thief. Thus a drunkard is not to be relied on either for true speaking, or honest principle; and therefore those who see that drinking leads to falsehood and dishonesty, never attach credit to what a drunkard says, nor trust him within reach of their property.

NATURALISTS’ CALENDAR.

Mean Temperature 40·44.