D199 Mr. Waldie’s investigations connected FNo. 3 
g } 
Chemistry of natural waters by Mr. T. Sterry Hunt, which will be 
found* well worthy of perusal. 
I am not aware whether much consideration has been given to the 
peculiarities of the constitution of such surface waters in regard to 
their mineral constituents and their action on the animal economy, 
except in the case of the abundance of earthy carbonates. This, 
however, is perhaps the least characteristic of these constituents, as 
many spring waters abound in earthy carbonates, or at least in earthy 
salts, sulphates and muriates of lime and magnesia. More charac- 
teristic is the deficiency of muriate of soda or chloride of sodium in 
the surface waters and its comparative abundance in spring waters. 
Soda is the characteristic alkali of the components of the human 
body, but some curious observations have been made by physiological 
chemists on the relative proportions of the two alkalies in different 
parts or tissues of the system; and though it is stated in these cases 
that the peculiarities exist entirely irrespective of the nature of the 
food taken, it would scarcely be warrantable to assume as certain that 
such differences in the predominance of potash or soda in food or 
drink are entirely destitute of influence. The point is at least worth 
bearing in mind, 
Phosphoric acid, when present, exists in such small quantity that only 
in very minute analyses is it sought for by the analyst. Silica is 
found much more generally. From its neutral and indifferent 
character, much attention has not been given to it in its influence 
on animal bodies. But attention has been given to all of these 
substances in relation to vegetable physiology, as plants draw their 
food directly from the soil in part at least, and the nature of its 
constituents is therefore of immediate importance. 
To the other constituents I have mentioned, namely organic matter 
with the products of its decomposition, including ammonia and nitri¢ 
acid, more attention has lately been paid in connection with water to 
be used for human consumption. Indeed this may be said to be the 
principal point to which the analysis of waters selected on sanitary 
considerations has of late been chiefly directed. 
The water of the Hooghly has a composition similar to that 
already given as that of river waters generally. According to Dr, 
* Sillman’s American Journal of Science for March, July and Sept. 1865. 
