65 
River phosphates. 
No.1. | No.2. | No.3. | No.4. | No.5. | No.6. | No.7. 
Moisture, water of combination, and loss 
upon ignition: 25. .-..---.-.--25-=4-----=- 4. 07 1.56 2.57 2. 64 1, 86 2. 89 2,58 
PHOS HNOTID AGIGs ser Loa ce SL. J. ak en -8 -2 28.44 | 26.89 | 27.11 | 26.97 | 26.89 | 27.44 25, 31 
Wet tte fons sa Sete So eS a Tee ct ee 45, 07 42.28 | 42.79 | 43.54 42.43 | 42.45 39. 37 
Magnesia, carbonic acid, oxide of iron, alu- 
Vn 7 ee ee ee wee tees vate bane 15. 16 18.47 | 17.54 17. 57 17. 39 17. 80 16.19 
Insoluble siliceous matter ...........--.---- 7.26] 10.80 9.99 | 10.28) 11.43 9, 42 16. 55 
_ 
100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 
* Equal to tribasic phosphate of lime..-. -..| 62.09 | 58.70| 59.18| 58.87| 58.70| 59.90 59. 25 
The rivers belong to the State, and hence their underlying deposits 
ean only be worked with consent of the legislature. Two companies 
have been incorporated for the working of this class of phosphates, 
upon which the State treasury receives a royalty of $l perton. The 
production of phosphates has been several years in operation, the first 
export of 6 tons being in 1867, and to American ports, from Charleston 
and Beaufort. The export rose, in 1868, to 11,862 tons, of which 208 
were to foreign ports; in 1869 to 28,271 tons,3,760 tons being shipments 
to foreign ports; in 1870 to 53,571 tons, 13,652 tons to foreign ports; 1871, 
64,792 tons, of which 42,923 tons were to foreign ports ; 1872, 47,623 
tons, of which 29,682 tons were for foreign trade. The total export up 
to that time was 206,305 tons, of which 90,225 tons were sent abroad. 
The foreign export had greatly surpassed the domestic export. . 
From the small uninhabited island of Sombrero, of the Leeward group, 
in the Caribbean Sea, a valuable rock-phosphate has for several years 
been imported into England, but, as the supply is growing small, it is 
feared that the accessible deposits have been mostly exhausted. The 
rock is now worked beneath sea-level, and at great expense, while 
the number of dangerous coral-reefs forbid the close approach of ships 
to land, rendering the shipment of the rock very difficult at.all times, 
and impossible during the stormy season, from September to January. 
Four cargoes imported into England during 1874 showed from 69.20 to 
71.65 per cent. of phosphate, and 12.68 to 16.64 per cent. of carbonate of 
lime, with ‘an average of less than 1 per cent. of insoluble siliceous 
matier. It is light colored, somewhat porous, and easily pulverized. It 
contains but little alumina or oxide of iron, and its increasing propor- 
tion of carbonate of lime seems to indicate that it is mined closer to 
the underlying coral-rock. It is very likely that the deposits hitherto 
worked are approaching exhaustion. 
Another uninhabited island in the Caribbean Sea, Navassa, seventy- 
two miles east of Jamaica, surrounded by coral-reefs, and hence of diffi- 
cult approach, supplies a mineral phosphate of reddish-brown color from 
the numerous cavities in its coral frame-work. It consists mostly of 
globular grains of phosphate of lime cemented into hard masses, and 
contaminated largely with oxide of iron and alumina. Its composition 
varies considerably. The lime in composition is insufficient to absorb 
all the phosphoric and carbonic acids, and hence a portion is united with 
oxide of iron or alumina. These elements always lower the commercial 
value of the mineral, inasmuch as the superphosphate made from it is 
poorer in character. The following detailed analyses of specimens of this 
mineral are given: 
SA 
