62 C. W. R. POWELL. 



Materials Used. 

 In the laboratory experiments steel wire was used 

 and Elliott Bros.' "Chemically Pure" sulphuric acid, 

 density 1*842. The steel wire was polished with emery 

 cloth before use and immersed in the acid with as little 

 delay as possible, so as to avoid the influence of impurities, 

 such as rust, coming into the reaction. 



In the first experiments conducted it was noticed, after 

 the sulphuiic acid had been acting on the steel for some 

 months, that the flask contained a large amount of a 

 whitish precipitate which was present in sufficient quantity 

 to obscure the steel. This was at first supposed to be a 

 complex compound of iron, sulphur and oxygen, but subse- 

 quent analysis proved it to be ferrous sulphate, in all 

 probability anhydrous, although it is just possible that it 

 consisted of the monohydrated salt. 



Methods of Analysis. 



The sediment from the flask was poured into a beaker 

 containing alcohol, and after being well mixed was filtered 

 through a Sox hie t filter paper. The paper was then placed 

 in a Soxhlet apparatus as used for fat extraction, and 

 washed with boiling alcohol. The washing was continued 

 for two days when practically the whole of the sulphuric 

 acid was removed. This method of purification was adopted 

 after trying others, and alcohol was found to be much pre- 

 ferable to any other solvent as a washing fluid. The acid- 

 free sediment was dried in a water bath at 100° 0. and 

 analysed gravimetrically with the following results : 

 Fe ... 32*8% 

 S0 4 ... 57-7% 



Adding up to ... 90*5 



If the formula be taken as FeS0 4 + H 2 0, that is mono- 

 hydrated ferrous sulphate, the total then adds up to 101*0, 

 which in this case is within the limits of experimental 



