64 
giving from 56.80 to 73.11 per cent. of phosphate. The less pure sorts 
are washed and sifted, yet a large proportion of the produce is too poor 
for profitable exportation, which requires at least 65 per cent. 
Phosphates have also been found in the valley of the Lot, a tributary 
of the Garonne, and in various localities in the south of France. It is 
known as the Bordeaux phosphate, and occurs in pockets, varying 
greatly in appearance, texture, and commercial value. Sometimes it 
occurs in snow-white compact masses, moderately hard, and with an 
earthy fracture, but more frequently it is opal-like, grayish, of a waxy 
luster, and conchoidal fracture. Both kinds arerich in phosphoric acid 
as well as those occurring in botryoidal masses or stalactic forms. The 
more ordinary kinds are yellow or brown, dense and hard, but readily 
decomposed by sulphuric acid, and adapted to the manufacture of high- 
grade superphosphates. The first specimens brought to England 
ranged from 71 to 74 per cent. in phosphate; but poorer qualities, rang- 
ing from 58 to 65 per cent., have of late years, been shipped. Dr. 
Voelcker concludes that either the best qualities are showing signs of 
exhaustion or that the increasing demand prompts the shipment of in- 
ferior varieties. The high-quality samples contain from 73.78 to 77.52 
per cent. of tribasie phosphate; medium quality, 63.35 to 69.16 ; inferior 
quality, 53.40 to 58.20. 
The calcareous strata around Charleston, South Carolina, abound in 
phosphatic nodules quite similar to the coprolites of the London basin. 
These strata underlie the city of Charleston and extend between the 
Santee and Ashepoo Rivers, covering an irregular area of fifty-five 
to sixty miles. Within this basin are found deposits of fossil-bones and 
other animal remains, rich in the phosphate of lime, but the chief sup- 
ply is found in nodules constituting from a third to a half of the strata 
in which they are embedded. They are generally found in detached 
deposits, at irregular intervals, along the streams. They are generally 
rough, irregular in form, water-worn, rounded, and light yellow or brown; 
they are somewhat cavernous and perforated by boring-shells. Fish- 
teeth and fragments of bones are frequently found with them. The 
land-deposits are lighter in color and softer than the river phosphates. 
Where embedded in and overlaid by sand it is. readily separated by the 
action of water; where embedded in clay the tenacity of its surround- 
ings renders it hard to disengage them. Later importations into Eng- 
land are better cleansed than previous ones. The following analyses 
illustrate the characters of land and river phosphates respectively: 
Land phosphates. 
® No.1. | No.2. | No.3: | No.4. | No.5. | No.6. | No.7. 
Me PA oe TREES NILES ANS 2 | f 6.59| 7.69 
Water of combination.................-.- 5 7.40 2.29 | 10.30 3.98 8. 01 1.09 1, 34 
TPBOSPHOPIG AGG Ai cite noi meneame gaan eel sa 26. 50 24.29 | 22.06} 25.47} 23.93; 24.80 23. 35 
NMG aoe eee cee. acne seamabce = ses same 37.20 | 38. 71 37. 24 40. 11 36.75 | 38. 84 36. 41 
Oxide of iron and alumina, magnesia, car- 
GDI ROM OLE eo siaccccn aw eisasin= nicdaonyis ms 16.27} 17.28] 15.45] 18.82{ 16.88] 17.01 16. 54 
Insoluble siliceous matter ....--.-.--..---.- 12,63 | 17.43 | 14.95] 11.62] 14.43] 11.67 14. 67 
100. 00 | 100.00 | 100. 00 | 100.00 | 100.00 | 100.00 | 100.00 
* Equal to tribasic phosphate of lime....... 57.85 | 53.02 | 4816| 55.60] 52.24] 5414] 50.98 
It is probable that the low per cent. of phosphate in the above cargo 
specimens is due to the excess of water in the cargo, or to failure to 
wash it with sufficient care from adherent sand. 
