64 Analyses of Books. 



rate the water through which it passes in order to collect it ; the 

 liquid being conducted into shallow troughs, where it is mixed with 

 soda, by which addition crystals of borax are obtained from it as the 

 aqueous portion escapes. 



" Now, when we compare together the eftects produced by the 

 disengagement of steam and sulphuretted hydrogen, owing almost 

 unquestionably to a volcanic cause, in the instance before us and in 

 that of the Lake Amsanctus, we are naturally led to apply the same 

 explanation to those immense deposits of sulphur which occur on the 

 western side of Sicily. If any doubt should exist as to the fact of 

 their having been so produced, it may be removed by reflecting, that 

 we know of no instance of sulphur being sublimed in uncombined 

 form by volcanic action, and that seems scarcely possible for such an 

 event to occur, without the combustion of the sulphur taking place 

 the instant of its comming into contact with atmospheric air. 



'• Hence it may be inferred, that the whole of this vast deposit in 

 Sicily has been occasioned by a decomposition of sulphuretted hydro- 

 gen gas, such as has taken place on a smaller scale at Lake Amsanc- 

 tns, and has there impregnated the surrounding rocks with crystals 

 of the same material. 



" In Sicily too we meet with all the combinations which sulphuric 

 acid is capable of forming with the earths present — in the beds of sul- 

 phate of lime, of strontian, of barytes, of magnesia, that occur — there 

 also we see in the immediate neighbourhood warm springs impreg- 

 nated with sulphuretted hydrogen — memorials, as it were, of the 

 cause, which had produced these deposits. 



" May we not also be led to conjecture, that the gypsum so com- 

 monly present in the tertiary clay of Volterra and the maremnse of 

 Tuscany, has been produced by the same process, especially when we 

 find this clay associated, as it frequently is, with beds or nests of sul- 

 phur. 



" Thus the formation of the blue clay, in Sicily and in the ma- 

 remnae of Tuscany, would have taken place, not only on the same 

 epoch, which is generally admitted to have been the case, but under 

 the same physical conditions, one as the other, and a volcanic action 

 similar to that going on at the Lago d' Ansanto and at Monte Cerboli 

 would likewise have given rise to the deposits, which the former 

 contain, in common with the rocks found immediately round the 

 spots, where the above operations are at present proceeding. 



" But there is another circumstance also worth noticing, although 

 the inference to which it seems to point will scarcely receive admis- 

 sion until further proof can be adduced in support of it. I allude to 

 the association of salt springs with gypsum and sulphur both in Tus- 

 cany and Sicily. Their occurrence in such localities as these might 

 induce us to conjecture, that the same volcanic action, which pro- 

 duced the sulphuric salts, and volatilized the sulphur, has been instru- 

 mental also in separating the salts from its solution in water, and 

 thus serve to explain, in these instances at least, the puzzling fact, 

 that rock-salt is found associated, as is so commonly the case, with beds 

 of gypsum. The connexion between the above phenomena may per- 

 haps be seen more clearly by the following tabular view ; 



