Solutions of Metallic Salts. Ill 



Salts used. 



Precipitates. 



Degree 



of Precip 



MnS0 4 



AuCl 3 



(NH 4 ) 2 Mo0 4 



Sulphides. 

 MnS + S 



Au 2 S + S 

 MoS 3 (?) + S, Red 



liquid 



Partial, 



u 

 a 



BeCl 2 



Hydroxides. 

 Be0 2 H a 



Undetermined. 





a 



(NH 4 ) 2 U 2 7 

 K 2 FtCl 6 



CeCi 3 

 CaCl 2 

 SrCl 2 

 BaCl 2 



Black 

 Gray, reddish brown liquid 

 White, yellow liquid 



it t{ u 



a a a 

 a a a 



a 

 a 



a 

 a 



a 



MgS0 4 



NH 4 V0 3 



]I o KAs0 4 







Trace. 



Brown liquid 



A perusal of this table brings to light several interesting 

 facts. It appears that salts of nickel, cobalt, iron, zinc, lead, 

 mercury, silver, copper, cadmium, antimony and bismuth are 

 completely precipitated as sulphides by sodium thiosulphate 

 under the prevailing conditions of temperature and pressure. In 

 the case of manganese precipitation is only partial, and arsenic 

 does not seem to be precipitated from an arsenate without the 

 addition of acid. Tin, curiously enough, is not thrown down as 

 the sulphide from a stannous salt, but gives a dirty white precipi- 

 tate of uncertain composition. Salts of aluminum, chromium, 

 titanium, zirconium and thorium are completely precipitated 

 as the hydroxides ; but in the case of beryllium, which one 

 would expect to act similarly, the precipitation as the hydrox- 

 ide is incomplete. Salts of selenium and tellurium are re- 

 duced, and the elements are precipitated. The precipitates 

 obtained with barium, strontium and calcium were white in a 

 bright yellow liquid, but no study was made of the constitution 

 of precipitate or liquid. In the case of magnesium there 

 was no precipitate. Salts of molybdenum, vanadium and ura- 

 nium gave dark- colored liquids. Thallium yielded a white 

 spongy mass which on compression was reduced to a very small 

 bulk without disintegrating. Salts of gold and platinum gave 

 slight dark precipitates, presumably sulphides, surrounded by 

 dark-colored liquids. 



The apparatus used in these experiments and described 

 above is easily handled and answers sufficiently well for quali- 

 tative purposes. But, obviously, the introduction into pre- 

 cipitates of foreign matter caused by the action of water on 



