Mineral Sulphides of Iron. 



201 



Table V. 



Sulphur dissolved by FeS in an atmosphere of H 2 S 

 at measured temperatures. 



Temperature 



Time of heating 



Time in which 

 equilibrium 

 was reached 



Total 



Percentage of 

 dissolved 

 sulphur 



1 



600° 



12 h. 



15 h. 



6-04 



2 



800° 



3 " 



7 « 



4-41 



3 



1000° 



2 " 



4 " 



3-6 



4 



1100° 



2 « 



4 " 



3-3 



5 



1165° 



1 " 



2 " 



3'2 



6 



1200° 



20 min. 



H" 



2'5 



7 



1300° 



20 " 



i « 



1-96 



Table VI. 



Sulphur in pyrrhotite cooled in nitrogen from 

 various temperatures. 





Temperature 



Time of heating 

 in H 2 S 



Percentage of 

 dissolved sulphur 



1 



1210° 



Few minutes 



•41 



2 



About 1200° 



l|h. 



•63 



3 



1000° 



6 h. 



2-70* 



4 



900° 



6 h. 



3-11 



5 



800° 



6 h. 



3-74 



6 



700° 



2|h. 



4-14 



7 



600° 



3 h. 



4-77 



* The sulphur in No. 3 was calculated from the density. 



tion from which we judge the maximum quantity of sulphur 

 in pyrrhotite obtained by heating in hydrogen sulphide must be 

 about 6*5 per cent. If we compute the analyses of natural 

 pyrrhotite in terms of FeS and S, we find that the limit of solu- 

 bility agrees well with this. The highest value calculated from 

 Lindstrom'sf figures is 6*08 per cent. From Rose's:}; analyses 

 we derive the value of 6*76 per cent. The maximum percentage 

 of sulphur in the pyrrhotite analyses quoted by Dana§ is 40'46 

 per cent. This particular occurrence, however, contained about 

 0*5 per cent of copper and cannot, therefore, be satisfactorily 



fLoc. cit. 



j Gmelin Kraut Handbuch der Ch., 6th Ed., Vol. Ill, pt. 1, 332. 



§ System of Mineralogy, 6th Ed., p. 74. 



Am. Jour. Sci.— Fourth Series, Vol. XXXIII, No. 195. — March, 1912, 

 14 



