I 
used for Agrictiltural Purposes. 
417 
with an earthy fracture. More frequently it has an opal-like 
appearance, a greyish colour, a waxy lustre, and conchoidal frac- 
ture. The white and opal-like specimens I find are very rich 
in phosphoric acid, as are also those which occur in botryoidal 
masses, or stalactitic forms. 
The more ordinary kinds have a yellow or brown colour ; 
they are dense and hard to grind, but readily decomposed by 
sulphuric acid, and well adapted for the manufacture of high 
grade superphosphates. 
Inferior samples usually have a dark brown colour, or they 
appear as mottled and irregular masses or breccias, closely re- 
sembling some descriptions of Lahn phosphate, from which they 
are hardly distinguishable in appearan.ce, or by their chemical 
composition. 
When French phosphate was first brought into the English 
market, it frequently contained over 74 per cent, of phosphate 
of lime, and rarely less than 71 per cent. It would appear 
that at first only the richer deposits were worked in France 
and sent over to England, probably with a view of securing a 
good reception to the newly discovered deposits. 
I The percentage of phosphate of lime in high quality samples 
examined by me during the last two years has been somewhat 
lower than formerly ; and cargoes containing on an average not 
more than from 58 to 65 per cent, are now not unfrequently 
shipped at Bordeaux for the English market. It thus appears 
that either the best quality of French phosphate is already 
becoming somewhat scarce, or that the increasing demand for 
phosphatic materials necessitates the exploration of the more 
abundant deposits of an inferior quality. 
I have not seen anywhere a full analysis of Bordeaux phos- 
phate ; I therefore subjoin the results (p. 418), which I obtained 
in carefully analysing two cargo-samples which I received in 
1872. 
The sample No. 1, it will be seen, contained 77 J per cent, 
of phosphate of lime, a little oxide of iron and alumina, and 
about 4 per cent, more carbonate of lime than the second 
sample, which also contained but little oxide of iron, but a good 
(leal of alumina. 
In the next place I put on record a few analyses of high, 
medium, and low quality samples, all taken from cargoes im- 
]>orted into England during the current year. 
All these samples rank with the highest class of mineral 
phosphates ; some apparently contain rather more carbonate of 
lime than others, but all contain but little iron and alumina. 
liThey all had a light yellowish-grey colour. 
