LOWER CHALK—CHEMICAL COMrOSITION. 
337 
near Cambridge, No. 2 from Poplar Hall Horningsey, and No. 3 
from the late Mr. Colchester’s cement works at Hauxton. 
No. 1. 
No. 2. 
No. 3. 
Insoluble siliceous 
matter 
_ 
■« 
16 *6 
11-98 
22'20 
Carbonate of lime 
- 
- 
- 
69*0 
84-41 
72-18 
Carbonate of magnesia 
- 
- 
1 *8 
1-11 
* 75 
Sulphate of lime 
•29 
Alumina 
- 
- 
- 
1-0 1 
Oxide of iron 
T 
- 
- 
2*7 f 
1 '49 
2 * 50 
Alkali and traces 
of organic 
matter 
- 
2*3 
1 -01 ) 
Moisture 
•* 
- 
- 
6*6 
— J 
2'08 
V- 
100-0 
100-00 
100-00 
It should be notified that the first sample was analysed while still moist, 
and that if this moisture is allowed for, so as to compare with the other 
analyses, the proportion of carbonate of lime will become 73*87 per cent. 
The following analyses have been made of the lowest beds of the 
Lower Chalk in North-west Norfolk and Lincolnshire, where these 
beds have the same lithological characters. 
A and B were samples of the basement bed (“ Sponge-Bed ”) at 
Hunstanton (A being from the very base) and were analysed by 
Dr. J. W. Johnstone. They are quoted from a paper by Professor 
T. McK. Hughes in Quart. Journ. Geol. Soc., vol. xl. p. 278. 
C, D, and E were samples of the Inoceramus -Bed (see p. 283), 
C being from near (Layton in Norfolk, D from Hunstanton, and 
E from Gaumer Hill in Lincolnshire. C and D were analysed 
by Dr. W. Johnstone (see Proc. Norwich Geol. Soc., Vol. i., Part viii. 
p. 238 (1884), and Quart. Journ. Geol. Soc., Vol. xliii. p. 587). E 
was analysed by Mr. M. Staniland (see the Geology of East Lincoln¬ 
shire, Mem. Geol. Surv. (1887), p. 33). 
Sponge-Bed. 
Inoceramus-Bed. 
A. 
B. 
C. 
i 
D. 
E. 
Moisture and organic 
matter - 
trace 
trace 
1*112 
1 -40 
•56 
Carbonic acid 
41 -45 
42 • 29 
38-650 
40*54 
41 *71 
Phosphoric acid - 
•27 
•29 
2-522 
*16 
) not esti- 
Sulphuric acid - 
trace 
trace 
•663 
*09 
J mated. 
Lime - 
52-05 
53 • 23 
47*250 
51 -50 
52-44 
Alumina - 
trace 
•35 
trace 
•35 
— 
Peroxide of iron (Fe 2 0 3 ) 
•63 
•32 
— 
•50 
1-50 
Ferrous oxide (FeO) - 
— 
— 
1-255 
— 
— 
Manganese 
— 
trace 
trace 
•47 
— 
Magnesia - 
*77 
•75 
•601 
•25 
•70 
Sodium chloride 
— 
trace 
•058 
•75 
— 
Insoluble residue 
5-02 
3-17 
7-554 
3*38 
3-01 
100*19 
100-40 
99-665 
99-39 
99-92 
