Note 71 — (Second Pilgrimage.) (continued 2)

Note from Mr. Spitta.

I brought home one of the pretty stamps, made of Sprudelstein; and had the cruelty to break it up for chemical examination. I found it to be composed, as stalactites in all parts of the world are, of the earthy carbonates; which, originally held in solution by carbonic acid gas, are precipitated on its escape. The Sprudel contains a very small quantity of carbonic acid, only sufficient, as Beecher has observed, to keep its earthy carbonates in solution. As the water approaches the exit of the cauldron, and the gas ceases to be under pressure, it resumes its wonted elasticity, passes quietly off with the vapour which issues from the boiler, and leaves its irony carbonates, sticking to the edge of the reservoir. Carbonate of lime is the main ingredient of the Sprudelstein—it contains besides, carbonate of magnesia and iron; to the latter, its reddish-brown colour is to be attributed. There is a portion of iron also, as peroxyde; and minute traces of one or two other substances. With regard to the incrustations: they are nothing more nor less than petrifactions (as they are called), made exactly in the same manner as other petrifactions, by the deposition of the earthy carbonates. The difference in colour from other petrifactions arises from the difference in the composition of the Sprudel water and the water in other parts, where the white incrustations are formed. The Sprudel contains a small quantity of the carbonate of iron. This is deposited with the carbonates of lime and magnesia; and hence the brown colour.