Phosphatic 3faterials used for A(jricultural Purposes. 359 
stituonts, and to render the insoluble phosphates completely 
soluble. 
This precaution is not always observed by manufacturers, and 
hence superphosphate made from coprolites is often of an inferior 
<piality. Properly dissolved, they are converted into a most 
efficacious turnip-manure, for soluble phosphate of lime made 
from coprolites is in every respect as good as soluble phosphate 
made from bone or any other source. 
4. Suffolk Coprolites (Pseudo or False Coprolites). 
These phosphoric deposits occur in the more recent tertiary 
strata, as a layer varying from three to eighteen inches in thick- 
ness, between the coralline crag and London clay. The Suffolk 
crag is exceedingly rich in fossils, consisting partly of the frac- 
tured and rolled bones of cetaceous and other animals, with some 
fish-teeth, and chiefly of rolled water-worn pebbles, which were 
formerly supposed to be the fossilized excrements of saurian and 
other animals, for which reason they were called coprolites. 
Professor Buckland, however, showed that they are not true 
fossil excrements, but in all probability calcareous pebbles which 
have undergone a peculiar metamorphosis, and become impreg- 
nated with phosphoric acid by long-continued contact with 
decaying animal and vegetable substances. 
The name pseudo or false coprolites, which Professor Buck- 
land proposed for them, has been generally accepted by the 
scientific world. In commercial phraseology, we have to under- 
stand by SufFolk-coprolites, or crag-coprolites, or pseudo-coprolites, 
the mixed fossil bones, fish-teeth, and phosphatic pebbles which 
occur in the Suffolk crag. 
These phosphatic matters are distinguished from the grey- 
coloured chalk-coprolites by a brownish, ferruginous colour, and 
a smoother appearance. They are very hard, and yield on 
grinding a yellowish-red powder. 
Analysed in the manner usually adopted in commercial analyses, 
the composition of several samples of ground Suffolk coprolites 
may be illustrated by the following tabulated results : — 
General Composition of Suffolk Coprolites. 
No. 1. 
No, 2. 
No. 3. 
No. 4. 
No. 
5. 
Moisture and a little organici 
4-61 
3-80 
4-11 
6-28 
4 
74 
56 '52 
60-21 
61-15 
GO-99 
44 
20 
Carbonate of lime, magnesia,] 
fluorine, &c. (determined byi 
25'95 
21-77 
22-39 
21-74 
20 
92 
Insoluble siliceous matter 
12-92 
14-22 
12-55 
10-99 
30 
14 
100-00 
100-00 
100-00 
100-00 
100 
00 
