638 
PHOSPHATES USED IN AGRICULTURE. 
analysis, gave me an enormous proportion of phosphate of 
lime—in fact, it was chiefly formed of this substance and 
fluorspar—though it was not apatite ; * and I learned after¬ 
wards that Mr. Thomas Way had formerly examined several 
fossil polyps, sponges, &c., from the Green Sand, which gave 
a very large per-centage of phosphate of lime. 
This proves to us that a great amount of phosphates has 
been diffused through the Upper Green Sand formations, 
may-be by the accumulated excrement of myriads of fish and 
large reptiles which inhabited this country at the remote 
geological periods to which these formations belong. 
I have since analysed many other sedimentary rocks and 
fossils, in order to discover whether they contained any 
notable quantity of phosphate of lime, but rarely found more 
than one or two per cent., frequently a mere trace only. 
However, there exist, doubtless, other sources of phosphate 
yet to be discovered. 
If we admit that the mineral phosphate Sombrerite and 
that of Monk Island be similar minerals, and have been de¬ 
rived, by some unknown geological process, from guano; if 
we admit, moreover, that the coprolites found in Cambridge 
and Suffolk are, like those of the Coal and Lias formations, 
true fossil excrements, mixed here and there with bone ; and, 
thirdly, if we admit that the other numerous and above- 
named fossils (wood, sponges, polyps, &c.) fossilized by phos¬ 
phate of lime, be the result of an impregnation of organic 
substances by the excrementitious matter of animals now 
extinct, what a splendid example we have here of applied 
paleontology. For since agricultural chemistry began its rapid 
development, all these “ fossil excrements’* have become 
valuable as a means of aiding us to keep up the fertility of 
our soils, to increase our wheat crops, and to have an abun¬ 
dant and cheap supply of bread. We are thus tempted to 
class all phosphates used in agriculture, including bones, 
bone-ash, &c., as derived from organized beings that have 
once flourished upon our globe. 
But we have another source of phosphate of lime in the 
coarse variety of apatite of Estremadura, which appears to 
have had no connection with organized beings of any descrip¬ 
tion, and cannot be considered as a fossil. The Estremadura 
phosphate met with in commerce is the mineral apatite in 
the massive form; it is abundant in Spain, and may be in 
other countries also, but up to the present time it does not 
appear to be so plentiful as the other phosphates mentioned 
* See ‘ Report of British Association/ 1861, and ‘ Chemical News/ 
1861. 
