440 Transactions.—Chemistry. 
The alkaline ones differ from those of this class which have been already 
described in being silicated 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 present in the water when situated 
ata 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. When 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 European 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 earbonie acid has been wholly eliminated ; but in 
this ease a so-called mineral 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 siliea 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 will 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 distriet of Napier, which were presented to this department 
in June, 1878, by Dr. W. I. Spencer. 
. 
CT. NER Se eee pe 
