440 . Transactions, — Chemistri/. 



The alkaline ones differ from those of this class which have been ah-eady 

 described in being siHcated instead of carbonated. They are, in fact, 

 eminently siliceous waters comparing with the hot spring water of Iceland ; 

 any carbonic acid which may have been x^resent in the water when situated 

 at a great depth, being eliminated therefrom as it reached the surface, in 

 consequence of the superior affinity of silicic acid for alkaline bases at 

 elevated temperature and low pressure. 



This substitution of silicic for carbonic acid will only affect the waters 

 for therapeutic purposes where they depend in part or wholly for their 

 desired effect upon the presence of carbonic acid. AVhen the alkaline 

 character of the water, however, is alone to be regarded, I do not see why 

 these silicated waters of ours should not (when of about the same strength) 

 be quite as useful as those alkaline waters of the Euro]oean spas in which the 

 alkalies are combined with carbonic acid, and when neither iodine nor 

 lithium are present to any notable extent. The waters of this kind are 

 Nos. 1-6. 



The waters of the other class — the acidulous — are also remarkable as 

 being those from which carbonic acid has been wholly eliminated .; but in 

 this case a so-called mmeral acid, hydrochloric or sulphuric acid, is the 

 substituting one in place of silicic acid as in the waters of the former class. 

 Silicic acid is, however, generally present, but in a free state as a hydrate, 

 all the silica which is entered in the analytical results of these waters being 

 of the kind known as soluble silica. The waters of this class are Nos. 

 8-15. Certain of these are hepatic, some strongly so, that is, they contain 

 sulphuretted hydrogen in quantity, and it is only the waters of this kind 

 which it would be safe as yet to look upon as having useful medicinal 

 qualities to a remarkable degree. 



These waters are Nos. 8, 9, 11, and 13-15, or those of Kauwhanga, 

 Cameron's Bath, Te Kauwhanga, Sulphur Bay Spring, Ti kute, and Te 

 mimi, Okakahi, respectively. 



These waters should prove efficacious in cases of rheumatism and skin 

 diseases. The more palatable ones wih of course be those which are the 

 least acidic. 



I cannot find that these waters strictly compare with any of those 

 afforded by the European spas ; the free hydrochloric or sulphuric acid 

 present in them clearly separating them therefrom. 



11. — Taupo Mineral Waters. 

 I now have to describe a series of twelve waters from various hot springs 

 in the provincial district of Napier, which were presented to this department 

 in June, 1878, by Dr. W. I. Spencer. 



