Mineral Wafers of the Baths of Nevis, West Indies. S 



I need hardly remark, that the carbonate of lime which 

 the water contains is deposited on the escape, or expulsion, 

 or neutralization of the free carbonic acid. It is worthy of 

 remark, that a little silica, with a trace of phosphate of lime, 

 is deposited at the same time. It is also worthy of remark, 

 that when the bicarbonate of potash (a rare ingredient in a 

 mineral water), was obtained by evaporation to dryness, thus 

 insuring the removal of the excess of carbonic acid, — -.on its 

 being redissolved, almost the whole of the silica remained, 

 forming a strongly adhering incrustation of a dead white 

 colour. 



These, and other facts on the direct action of carbonic 

 acid on silica, some of which I have noticed in a paper lately 

 communicated to the Royal Society of London, would seem 

 to prove, that carbonic acid is capable of dissolving silica. 

 As this is a matter of importance, it may perhaps be right 

 to be more particular in describing some of the results. I 

 shall notice two in particular. 



A bottle with a glass stopper, two-thirds full of Nevis 

 water, after having been kept many months, was carefully 

 observed. Corresponding to the surface margin of the water, 

 a line of deposit was found of white matter without lustre, 

 mixed with minute crystals, with which the inside of the 

 vessel was studded below. The water was next poured out, 

 and the incrustation examined. It consisted of silica and 

 carbonate of lime chiefly ; the former remaining after the 

 action of dilute nitric acid on it, and washing with water. 

 It was best seen when dry, for when wet it was scarcely 

 visible. Under a high magnifying power, it appeared in part 

 crystalline, but more generally in delicate laminae. 



The water poured out of the bottle, on admixture with 

 ammonia, became turbid. After standing some time a de- 

 position took place from it on the sides of the glass vessel, 

 and this deposit also had the properties of a mixture of car- 

 bonate of lime and of silica; thus, after having been dried, 

 the carbonate of lime, on the application of an acid and water 

 was removed, whilst the silica in the form of a most delicate 

 incmstation, remained, having resisted the action of the nitric 

 acid and water. 



