OF IRON-STONE. VICKERY. 211 



The specimen used in the following analysis was pro- 

 cured from the grounds at Studley. It was quarried from 

 across the North West Arm, near Halifax, in the old King's 

 Quarry, a few hundred yards from the contact with the granite. 

 It was slightly mineralised but care was taken to select a 

 specimen which had not been weathered to a sufficient extent 

 as to become stained. By the courtesy of the Technical 

 College it was reduced to a very fine flour in their machines, 

 and was then very carefully mixed. The actual specimen 

 analyzed was obtained by selecting small portions from all 

 parts of the mass, and these portions were again ground in 

 an agate mortar until no grit was perceptible. A weighed-out 

 portion of this was taken and thoroughly mixed with about 

 eight parts of sodium carbonate, placed in a platinum crucible, 

 and two more parts of sodium carbonate placed on top. 



The crucible was heated gently at first and then more 

 violently until a clear fusion took place, the crucible being 

 meanwhile loosely covered. On cooling, the crucible and its 

 cover were placed in a solution of 50 CC hydrochloric acid in 

 100 CC of water and allowed to thoroughly disintegrate. The 

 residue of silica was filtered off and washed, and the filtrate 

 evaporated to dry ness and dehydrated on the water-bath for two 

 hours, the residue moistened with concentrated hydrochloric 

 acid, and dissolved in about 150 water, filtered and 

 washed. 



A second evaporation and dehydration was found neces- 

 sary in only a few cases. The silica was carefully ignited 

 to constant weight. It was then treated with a few drops 

 of concentrated sulphuric acid and hydrofluoric acid and 

 warmed to expel the silicon tetrafluoride and finally the sul- 

 phuric acid and the crucible again weighed. The difference 

 of these two weighings gave the silica contents of the iron- 

 stone which was found to be 58.05%. The residue in the 

 crucible, which was chiefly iron and aluminum oxide, amount- 

 ed to .0140 g. and as an even gram portion had been taken 



