116 Norton — Action of Sodium Thiosulphate on 



It was shown by Dr. G-ibbs that when the treatment of salts 

 of aluminum by thiosulphate was carried on in sealed tubes under 

 pressure at 120° C, the precipitation of alumina was complete, 

 and further that the precipitation of sulphides of nickel, cobalt 

 and iron, though partial under ordinary atmospheric pressure, 

 was made complete by heating in sealed tubes to 120°-140° C. 



In repeating the experiments of Dr. G-ibbs qualitatively and 

 extending them, I have made use of the well-known Pfungst 

 tube to secure the necessary pressure. In each experiment a 

 test tube containing the mixture of an excess of sodium thio- 

 sulphate with the salt whose action was studied was placed 

 within the Pfungst tube containing some water, the cover of 

 the latter was set in place and firmly bolted upon a washer of 

 lead, and the whole was submitted to temperatures varying 

 from 140° to 200° C. for an hour by immersing in a bath of 

 paraffine. After cooling, the test tube was taken out, the pre- 

 cipitate was filtered off, and the filtrate tested by appropriate 

 reagents to determine the completeness of precipitation. The 

 following table records the details of these experiments : 



Action of Na„S„0 o on Salts under Pressure. 



Salts used. 



Precipitates. 





Sulphides. 



NiS0 4 



NiS + S 



CoS0 4 



CoS +S 



FeCl 3 



FeS + S 



ZnS0 4 



ZnS + S 



Pb0 2 (C 2 H 3 0) 2 



PbS + s 



Hg(N0 3 )., 



HgS + S 



AgNO, 



Ag 2 S + S 



CuS0 4 



CuS,(Cu 2 S), 



CdS0 4 



CdS + s 



KSbC 4 H 2 7 



Sb 2 S 3 + s 



Bi(N0 3 ) 3 



Bi 2 S 3 + S 





Hydroxides. 



NH 4 A1(SQ 4 ) 2 12H 2 



A10 3 H 3 + S 



K 2 Cr 2 7 



CrO.H, + S 



K 2 ZrF 6 



Zr0 4 H 4 + S 



<™ 6 



Ti0 4 H 4 + S 



Th(N0 3 ) 4 



Th0 4 H 4 + S 





Elements. 



Se0 2 



Se + S 



TeO, 



Te + S 



Degree of Precipitation, 



Complete. 



+ S 



