214 NOTES ON THE ANALYSIS 



the filtrate diluted to 40CT brought to boiling and hot barium 

 chloride solution added very slowly in slight excess and the 

 solution allowed to digest for some hours. From the precip- 

 itate of barium sulphate the sulphur content was calculated 

 and found to be 1.67%. 



The water contained in combination was estimated by 

 igniting a fresh sample for some hours in a covered crucible to 

 constant weight. This was found to give a proportion of 

 volatile matter of 6.49%. As this, however, probably in- 

 cludes the sulphur a determination of the sulphur contained 

 in the residue was made showing that over two-thirds of the 

 total sulphur had been driven off. This weight subtracted 

 from the total loss of weight on ignition gave the loss due to the 

 volatilization of the water which was found to amount to 5.23%. 



These results may be summarized as follows: 



" IRON-STONE." 



Silica. . 58.05 



Combined Oxides: Alumina 26.02 

 Ferrous Oxide 1.72 

 Ferric Oxide 4.51 32.25 



Calcium Oxide 67 



Magnesium Oxide . . .^ 1.18 



Sulphur 1.67 



Water 5.23 



99.05 



A partial analysis of another sample of iron-stone was 

 made, the specimen being taken from a rather silicious band 

 very near the granite contact and with the minerals quite 

 highly developed. The results were: 



Silica 64.48 



Combined Oxides 26 . 06 



Sulphur 32 



Magnesium Oxide 1 . 56 



Volatile matter, including water and 



probably some sulphur 2 . 68 



