96 



PROCEEDINGS OF THE AMERICAN ACADEMY 



with hydrosulphuric acid and oxide of tin are both represented in the 

 numbei's below. 



" The action in ten days' exposure was inconsiderable. No coat 

 formed on the tin. 



" A portion of Cochituate water that had been standing two months 

 in tin pipe, which was kindly furnished last February by the engineer 

 of the water-works, was evaporated to dryness with carbonate of soda, 

 and gave with the blowpipe a malleable metallic button. Tlie precip- 

 itated oxide from this water, that from distilled water acting upon 

 chemically pure tin, and that from Cochituate and the various other 

 waters upon the impure tin, were identical in appearance. 



" Lehman remarks of the solubility of tin in solutions of sal-ammo- 

 niac, alum, and bisulphate and bitartrate of potassa.* ' Lindes has ex- 

 amined the solutions which by boiling attack tin vessels. According 

 to his experiments, tin is rapidly brought into solution, without precip- 

 itating the oxide by alum, sal-ammoniac, and bisulphate of potassa. 

 Without dissolving the oxide, but merely depositing it, chlorides of ba- 

 rium and calcium, neutral carbonate and bicarbonate of potassa, sul- 

 phates of potassa, soda, and magnesia, chloride of sodium, tartrates of 

 ammonia and potassa, and borate of potassa.' t These experiments 

 were made with the aid of heat. Time accomplished the same end in 

 all the waters I have employed, including distilled water, producing 

 either solution or deposit of the oxide, not upon the tin, but the bottom 

 of the containing vessel. Lindes did not observe that saltpetre acted 

 with the aid of elevated temperature. The time in his experiments 



* Taschcnhuch drr C/itmie, 1848, S. 192. 



t Berzelius, Jahresherkhl, Vol. XII., S. 110, 1833. 



