404 On the Chemical Composition of Phosphatic Minerals 
best description of phosphatic nodules, as the following analyses 
of recent cargoes will show : — 
General Compositiox of Cambridge Coprolites. 
No. 1. 
No. 2. 
No. 3. 
No. 1 
2-30 
) 
j 1-19 
113 
} = 
79 
1-50 
i 1-99 
2-87 
ZD UO 
29 
14 
ZO 1» 
43-68 
45 
05 
41-47 
41-91 
18-70 
19 
68 
19-42 
17-84 
7-77 
2 
34 
10- 13 
10-10 
*Equal to ti ibasic phosphate of lime . . 
100-00 
100 
00 
100-00 
100-00 
56-87 
63 
60 
56-32 
57-08 
The sample No. 2 is unusually rich in phosphate of lime, 
the three other samples fairly represent the average composition 
of the present supply of good Cambridge coprolites. 
Besides Cambridgeshire and Suffolk, the counties of Norfolk, 
Bedford, and Buckingham produce phosphatic nodules of various 
degrees of value to the manure-manufacturer. The following 
analysis represents the chemical character of a good sample ol 
Bedfordshire coprolites : — 
General Composition of BedfordsJ-ire Coprolites. 
Moisture and water of combination 3 • 35 
*Phosphoric acid 23*47 
Lime 30-29 
Oxide of iron 5-39 
Alumina, magnesia and fluorine 7-24 
-fCarbonic acid o-45 
Insoluble siliceous matter 20' yl 
100-00 
* Equal to tribasic phosphate of lime .. .. 51-24 
t Equal to carbonate of lime 7-84 
]\Iost of the diggings in Bedfordshire furnish brown-coloured 
coprolites, containing a good deal of oxide of iron, and resem- 
bling in their chemical character Suffolk coprolites. 
As a matter of curiosity, I quote an analysis of some beautiful 
specimens of fossil wood, which I found in a cargo of Bedford- 
shire coprolites : — 
