OF ARTS AND SCIENCES. 



81 



They were, however, not ignited and redissolved, as in the examination 

 of waters exposed in lead pipe, and the numbers were intended, as al- 

 ready remarked, to express only relative values. 



" Influence of Nitrates. — Although medical testimony and public 

 sentiment were conclusive upon the subject of the health of our larger 

 cities, so far as it might be influenced by the lead contained in the res- 

 ervoir-waters used for culinary and general purposes, it was equally 

 certain that individuals had been poisoned from drinking the waters of 

 wells, and in one case, at least, from drinking water from a spring. 

 It was obvious, therefore, that between these two classes, river, lake, 

 pond, and open reservoir waters on the one hand, and well and some 

 spring waters on the other, there must be differences in their relations 

 to lead. Experiments were made with well-water, and at the same 

 time with the river and lake waters in my possession. The following 

 result shows with what success. 



Table XIX. 



" The bars rested on the bottoms of the tubes, and the waters had 

 been some time standing in sunlight. These experiments threw little 

 light upon the subject. The differences in favor of the Cochituate ^and 

 Fairmount, as compared with a well-water known to act vigorously on 

 lead pipe, were too inconsiderable to be worthy of notice. These wa- 

 ters contained in 500cc. 



Of Solid Residue. 



Of Organic Matter. 



Of Inorganic Matter. 



0.0.540gr. 



0.0840gr. 



Well water, 0.1380gr. 

 Cochituate, 0.0267 0.0122 0.0145 



Fairmount, 0.3007 0.1032 0.1975 



" On comparing these, it will be seen that the water which con- 

 tained the most solid residue acted least on lead, and that the action of 

 that which contained least solid residue was next in order. The com- 

 parison of the analyses of waters made by different individuals led to 

 no satisfactory results. Ingredients that might have been presumed to 



VOL. II. 11 



