84 IOWA ACADEMY OF SCIENCES. 



be only one-half the amount of sodium present to produce 

 this much carbonate, and in practice there would be much 

 less produced than theory would indicate, there must still 

 have been a large amount of this salt to deal with. 



Alkaline nitrites have the power of absorbing carbon 

 dioxide and giving off oxides of nitrogen, thus changing 

 spontaneously into carbonates when conditions are favor- 

 able. It is also well known that nitrates are changed into 

 nitrites by the action of many reducing agents. In the 

 light of the above, then, the first step would probably be 

 the changing of the nitrate to nitrite by the reducing 

 action of the iron. In the second step the carbon dioxide 

 which has been formed replaces the " N^O," in two mole- 

 cules of sodium nitrite. 



Third. — The precipitates which Menke's sodium salt 

 yielded with various salts of the heavy metals are quite 

 different from those described by Divers, and quite identical 

 with those yielded by a solution of sodium carbonate. 



diver's hyponitrite. 



Copper sulphate gives a yellowish, olive green precipitate. 



Lead acetate gives a cream white, floculent precipitate. 



Mercuric chloride gives a cream white floculent precipi- 

 tate. 



Mercurous nitrate gives a blackish, gray precipitate. 



Nickel chloride gives a greenish, almost white, precipi- 

 tate. 



Manganese chloride gives a nearly white precipitate. 



Ferric chloride gives a reddish-brown precipitate. 



Ferrous sulphate gives a whitish precipitate which 

 instantly changes to a dirty, blackish green. 



Zinc chloride gives a white precipitate. 



Barium chloride gives no precipitate. 



* 



menke's "hyponitrite." 



Copper sulphate gives a torquois blue precipitate. 

 Lead acetate gives a white precipitate. 

 Mercuric chloride gives a white precipitate which be- 

 comes yellow and then brownish-red. 



