150 ON THE OXIDATION OF IRON. 



I shall here subjoin a tabular view of the nine successive 

 calcinations, that the reader may observe their progress. 



Gram. Gain. Loss. 



Tabulated re- The iron filings weighed 5 grammes* 



suits. and the capsule • 29*340 



Capsule and filings 34'340 



{After a calcination of 1 1 hour •• 34-885 0*545 

 After trituration 34*885 0*000 



{After a 2d calcination of 2 hours 35*100 0*215 

 After trituration 35*0i}0 0*010 



C After a 3d calcination of 3 hours 35*530 0*440 



I After trituration 35*520 0*010 



After a 4th calcination of 4 hours 36*380 0*860 



After trituration 36*370 0010 



{After a 5th calcination of 6 hours 36*420 0*050 

 After trituration *. 36*405 0*015 



5 After a 6th calcination of 4 hours 36*405 0*000 



\ After trituration 36*390 0*015 



After a 7th calcination of 3 hours 36*390 0*000 



After trituration 36*375 0*015 



After an 8th calcination of 2 hours ; 36*375 O'OOO 



After trituration 36*360 0*015 



After a 9th calcination of 1 hour 36360 0*000 



I 



Process of the From these experiments it follows, that the increase of 

 calcination tr- W eight by calcination was somewhat irregular in its progress, 

 and after the 5th calcination, which was continued for 6 

 hours, the oxide increased no more in weight, to whatever 

 temperature it was exposed. 

 Loss by tritura- It appears too, that in all the triturations, except the first, 

 t,on « the oxide of iron lost weight, owing to that evaporation 



which is unavoidable, when we triturate a very fine sub- 

 stance, and this evaporation appeared to follow a law de- 

 pending on the fineness of the particles of the oxide. At 

 first, while the particles were still coarse, it was nothing; 

 when they began to grow fine, it was 0*010; and when they 

 were still finer, it was 0*015. 



* 77 grains English. 



Calculating 



