350 IRON, NICKEL, COBALT, &c. 



sulphur is converted into sulphuric acid, while 

 the iron at the same time is oxydized. If the so- 

 lution, thus changed, be mixed with a sufficient 

 quantity of muriate of barytes, sulphate of ba- 

 rytes precipitates* the weight of which enables 

 us to determine the proportion of sulphur which 

 the protosulphuret of iron contains. 100 grains 

 of protosulphuret, treated in this way by Berze- 

 lius, yielded him 269 grains of sulphate of ba- 

 rytes.* This weight exceeds the truth a little ; 

 because a portion of the oxide of iron is precipi- 

 tated along with the sulphate of barytes, suffi- 

 cient to give it a reddish yellow colour. \Vhen 

 the oxide of iron is precipitated, in the first place, 

 by means of ammonia, and the requisite precau- 

 tions taken to prevent any of the sulphuric acid 

 from remaining in combination with this preci- 

 pitate, the sulphate of barytes is perfectly white, 

 and weighs almost exactly 267*3? grains. Now, 

 267'37 grains of sulphate of barytes contain al- 

 most exactly 36*36 grains of sulphur. Thus it 

 appears that 100 grains of protosulphuret of iron 

 contain 36 '36 grains of sulphur. Consequently, 

 the constituents of the protosulphuret are 



Sulphur 36-36 or 2 

 Iron . 63-64 - 3-5002 



100-00 



It is obvious that this protosulphuret is n com- 



* Ann. de Chim. LXXV1II. 12C. 



