OF ARTS AND SCIENCES. 



95 



" I. 50cc. of lead solution, containing one thousandth of its weight 

 of lead, witli lOcc. of cofTee-grounds, were boiled three minutes, and 

 the decoction poured off". The residue was drained through Swedish 

 filtering-paper, the filtrate added to the liquor poured off, and evapo- 

 rated to dryness, ignited, redissolved, treated with hydrosulphuric acid, 

 and the precipitate estimated as before. It had lost more than forty- 

 nine fiftieths of the lead. 



Originally in solution, 0.05gr. of lead. 



After separation from the grounds, 0.0009 " 



" II. 50cc. of solution, containing one tenth as much lead as that in 

 the last experiment, were boiled with 5cc. of coffee-grounds, and treat- 

 ed as above. It had lost more than eleven twelfths of its lead. 

 Originally in solution, O.OOSgr. of lead. 



After separation from the grounds, 0.0005 " 



" These results contribute to account for the circumstance mentioned 

 above. 



" Other Materials than Lead for Service-pipes. — I have re- 

 marked that this investigation was instituted chiefly with a view to de- 

 termine the trustworthiness of lead. Experiments have, however, to 

 some extent, been made with other substances. The general condi- 

 tions have been observed in experimenting with them that had been re- 

 garded with lead, namely, equal volumes of water to equal surfaces of 

 substance, that comparison might be instituted. 



" Table XXV. — Experiments with Copper TurniJigs. Water con- 

 centrated to one third of its volume. 



Days. 



1 

 11 



17 

 2.5 

 37 



Distilled 

 Water. 



0.01)1 

 1.000 



Albany. 



0.500 

 0.500 



Cam- 

 bridge. 



Cochit- 

 uate a. 



0.005 0.001 

 0.000,0.000 



0.000 0.001 



1.000 0.500 



0.00-2 1 0.050 



1 0.005 



Cochit- 

 uate 6. 



Cochit- 

 uate c. 



Croton. 



0.002 0.000 0.000 



1.000 1.000 



0.080 



0.05010.050 



O.OIO 

 0.002 



Fair- 

 mount. 



0.000 

 0.500 

 0.001 

 0.000 



Jamaica. 



0.001 

 0.010 

 0.050 



Troy. 



0.000 

 0.500 

 0.001 

 0.010 



" These experiments show only a feeble action of aerated water on 

 copper. 



" Table XXVI. — Experiments with Tin. — The tin contained arse- 

 nic as an impurity. Chemically pure tin yielded precisely the same 

 results when exposed to the same waters. Bars of size already men- 

 tioned. lOcc. of water concentrated to from 3 to 5cc. Precipitates 



