424 On the Chemical Composition of Phosphatic Minerals 
The Charleston river phosphate has a dark grey, almost 
black colour, and is much harder than the land phosphate. It 
generally contains a little iron pyrites, and when well washed 
and dried is fully equal to the best Cambridge coprolites for 
the manufacture of superphosphate, as the following analyses 
will show : — 
Composition of Cabolina Eiver Phosphates. 
No. 1. 
No. 2. 
No. 3. 
No. 4. 
No. 5. 
No. 6. 
Ko. 
2- 
25- 
sa- 
le - 
16- 
Water of combination and> 
loss on ignition . . . . j 
Magnesia, carbonic acid,"! 
oxide of iron, alumina, &c./ 
Insoluble siliceous matter . . 
* Equal to tribasic plios-l 
phate of lime . . . . / 
4-07 
28-44 
45-07 
15-16 
7-26 
1-56 
26-89 
42-28 
18-47 
10-80 
2-57 
27-11 
42-79 
17-54 
9-99 
2-64 
26-97 
42-54 
17-57 
10-28 
1-86 
26-89 
42-43 
17-39 
11-43 
2-89 
27-44 
42-45 
17-80 
9-42 
100-00 
100-00 
100-00 
100-00 
100-00 
100-00 
100 
62-09 
58-70 
59-18 
58-87 
58-70 
59-90 
00 
Most of the cargoes of Charleston river phosphate which have 
arrived in England during the last two years, I have found richer 
in phosphate of lime, and more valuable, than the great majority 
of the shipments of land phosphate, samples of which have, 
during that period, been sent to me for analysis. 
" The river deposit being mined from the navigable rivers, the 
property of the State can only be mined by consent of the 
Legislature, which has granted charters to two companies, re- 
quiring them to pay to the State one dollar per ton royalty for 
every ton mined and removed. This deposit is worked by 
hand from April to September, but the business proper is done 
by machinery, which is worked at all times of the year. And 
as the rock is raised through the water, either out wf the mud 
or sand, it is easily separated by the washers that accompany 
the dredges. This deposit furnishes the bulk of the supply 
now received." 
The preceding paragraph is taken from an official report com- 
piled and published by the Charleston Chamber of Comincrcc 
on the Trade and Commerce of the city of Charleston, S. C, Irom 
September 1, 1865, to September 1, 1872. 
The same Report gives some interesting statistics respecting 
the production and shipment of Charleston phosphates. Amongst 
other particulars it supplies'the following Tables: — 
