120 An ANALYSIS of 



and I mav offer what I have imagined, without its being thought 

 neceffary to make an apology. Profeffor Bergman confidered 

 the (iliceous earth in thefe waters as diffolved by the power of 

 the hot water alone ; and fuppofed, that water, aided by excef- 

 five heat, became a folvent of this fpecies of earth. He formed 

 this opinion, however, under difadvantageous circumftances, 

 and from a partial view of the fubject. He only knew that 

 this earth is actually diffolved in thefe waters, and depofited by 

 them, and that they fpring out of the ground of a full boiling 

 heat, with appearances of their having been hotter below. 

 He did not know what other ingredients they contained along 

 with the earth. As we now know they contain an alkali, 

 which is a powerful medium for combining this earth with 

 water, I do not think that the power of water alone to diffolve 

 it can be admitted, until it is proved by direct experiments ; 

 and I am not of opinion that thefe will fucceed. I am perfuaded 

 that both the (iliceous and the argillaceous earth have been dif- 

 folved by the medium of the alkali, but at the fame time that 

 the violent and long continued heat contributed greatly, and 

 was even neceffary to this diffolution. The proportion of the 

 •cauflic alkali to the earthy matter in one of thefe waters, is as 

 13^ to ico ; in the other it is 16 to 100. When we form arti- 

 ficial compounds of filiceous earth and alkali in thefe proportions, 

 we find that cold water has no power to diffolve them, though 

 boiling water, by length of time, would certainly act on them. 

 Even cold water, or the humidity of the earth, is well known 

 to penetrate the hardeft glafs that is expofed to it for years or 

 for ages ; and I have had the experience of the power of hot 

 water to act on glafs, when I have diflilled water in the fame 

 glafs retorts a great number of times, or evaporated water often 

 in other glafs-veflels. Their internal furface was evidently 

 affected by the continued action of the hot water. Its firft ef- 

 fect is to foften thin laminae at the furface of the glafs, and to 

 make them feparate from that furface, in confequence probably 



of 



