212 Mr. Wahlie's investigations connected [No. 3, 



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 nitric 

 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, 

 * Silliman's American Journal of Science for March, July and Sept. 1865. 



