APPENDIX V. 367 6*230 grm. of ore treated with nitric acid yielded after farther treatment 1*46608 grm. of insoluble matter, or 23*532% Mean .. .. 23*379% Of this amount of residue 1*46608 grm. there was found 0*21608 grm. of soluble silicic acid, which therefore was present in the ore as a silicate to the amount of 3*468% 23-379 grm. total residue— 3*468 grm. silicic acid = 19*911 % of insoluble sihcic acid in the form of quartz and sand.

3. Estimation of the Iron.

4'499 grm. of the ore were dissolved in fuming hydrochloric acid, the silicic acid separated, and the solution made up to 500"" ; 50""' of this solution (A) (corresponding to 0*4499 grm.

of substance) was reduced with zinc free from iron, and estimated with a solution of permanganate of potassium, of which 1'"" = 0*00688 grm. of iron or = 0*009828 grm. of oxide of iron.

29*2"" of the solution of permanganate of potassium were required. This test was repeated three times, and the result was the same in each case 29*2""" = 0*286977 grm. of oxide of iron, or 63*786 %.

4. Estimation of the Phosphoric Acid.

6*230 grm. of ore were treated with nitric acid, the sihcic acid removed, then well washed, and in the filtrate the phosphoric acid precipitated with molybdate of ammonia. The precipitate which resulted, after being washed and again precipitated with chloride of magnesium, gave chloride of ammonia, which after being heated to red heat gave 0*109765 grm. pyrophosphate of magnesium (Mgg P2 O7), corresponding to 0*0702 grm. jDhosphoric acid (P2 O5) or = 1*127 % P2 O5.