used for Agricultural Purposes. 433 
Composition of a Sample of Alta Vela Phosphate. 
Moisture 10 • 04 
Water of combination 5 " 85 
•rhospboric acid 2(1 • 45 
Lime 11-29 
f Carbonic acid 4 '01 
Oxide of iron 5 ■ 76 
Alumina 13 '48 
Insokible siliceous matter 28 '52 
100-00 
* Equal to tribasic pbosphate of lime .. 44 -Gl 
t Equal to carbonate of lime 9-11 
This sample was evidently a mixture of phosphate of alumina 
vith pbosphate and carbonate of lime, and a good deal of insoluble 
iliceous matter. 
Other samples I have found free from lime, but in all hitherto 
inaljsed by me I have found a considerable proportion of in- 
soluble siliceous matter. On the whole, Redonda phosphate is 
icher in phosphoric acid than Alta Vela phosphate, as will be seen 
!)y the following results of analyses made in my laboratory : — 
Composition of Three Samples op Alta Vela (St. Domingo) 
Phosphate. 
No. 
1. 
No. 
2. 
No. 
3. 
18 
51 
19 
33| 
4 
12 
19 
99 
20 
07 
26 
23 
10 
86 
7 
38 
7 
23 
2 
79 
21 
20 
20 
22 
21 
98 
32 
84 
26 
99 
27 
19 
100 
00 
100 
00 
100 
00 
* Corresponding to tribasic pbospliate of lime . . 
43 
81 
57 
20 
67 
37 
Alta \ ela phosphate is a harder rock than Redonda phosphate, 
and of a lighter colour. 
CONCLrSION. 
All the minerals described in the preceding pages are of little 
use lor agricultural purposes, except when they are treated with 
sulphuric acid. I am aware that some, for instance, German 
phosphates, have been usefully applied to the land simply in a 
finely powdered state, and no doubt in the immediate neighbour- 
hood where phosphatic minerals of a low quality are found, and 
