368 APPENDIX V.

5.—Estimation of the Argillaceous Earth.

The quantity of argillaceous earth was estimated by precipitation of 50"" of the solution (A) (corresponding to 044:99 grm. of ore) with ammonia, whereby the whole of the oxide of iron and argillaceous earth, together with the whole of the ijhosphoric acid, were precipitated.

Weight of the precipitate = 0-3183 grm., or 70-749 %.

From this is to be deducted 63-786 % oxide of iron + 1-127 % phosphoric acid = 64'913 %.

70-749 — 64-913 = 5-836 % of argillaceous earth.

Table of Results thus obtained from Oee No. 1.

In 100 parts of Ore there were After being heated at 100° the Ore contairj in 100 parts Water 3-040 Loss at red heat . . 2 • 929 3 • 020 , 67 Quartz and sand .. 19-911 20-533,21 Combined silicic acid 3-468 3-576,34 Oxide of iron , . .. 63-786 44-650% Iron. 65-782,50 45-957 % Iron. .

Argillaceous earth 1-127 6-018,66 Phosphoric acid .. 5-836 0-492 % Phosph. 1-162,27 • 5073 % Phospl 100-097 100-09 B. Iron Ore from Darfour, Central Africa. No. 2, found BY Robert W. Felkin, January 1880.

The second sample of ore appears to be a loose yellow-ochrecoloured earthy mass, which contained distinct traces of vegetable matter.

Like sample No. 1, the qualitative analysis shows the presence of— a. Oxide of iron.

b. Argillaceous earth.

c. Sand.