528 
THE CRETACEOUS ROCKS OF BRITAIN. 
Mr. R. A. Berry has kindly placed at my disposal the fol¬ 
lowing analysis of a sample of chalk from the zone of Bhynck. 
Cwvieri obtained by himself at Hitchin :— 
Calcium carbonate 
- 93*88 
,, phosphate 
*31 
Excess of lime 
- 2*91 
Magnesium carbonate - 
*67 
Oxide of iron and alumina - 
*27 
Manganese dioxide 
*58 
Colloid silica - 
•72 
Clay and quartz - 
*27 
Loss in analysis 
*39 
The excess of lime in this analysis is difficult to account for, 
and the amount of calcium carbonate is small compared with 
other analyses, but Mr. Berry only obtained 41*66 of carbonic 
acid from the material. 
Professor Barrois has published an analysis by M. Duvillier of 
a sample of nodular chalk from the zone of Rhynchonella Cuvicri, 
obtained by him from St. Catharine’s Hill, near Winchester ; it 
is as follows (see “ Recherches,” 1876, p. 41) : — 
Clay and sand - 
- 
- 
- 
- 
*72 
Soluble silica 
- 
- 
- 
- 
*06 
Oxide of iron - 
- 
- 
- 
- 
. -20 
Phosphate of lime 
- 
- 
- 
- 
•12 
Carbonate of lime 
- 
- 
- 
- 98*35 
Carbonate of magnesia 
•40 
99*85 
The following analysis of the Beer Stone of Devonshire was 
made by Mr. Charles Ekin, F.I.C., F.C.S., who kindly places it at 
our disposal. The sample was taken from the quarry by himself 
in 1899. When thoroughly air-dried it yielded— 
Silica and silicates 
- 
- 
- 
4-18 
Ferricoxide and alumina 
- 
- 
- 
*76 
Carbonate of calcium - 
- 
- 
- 
- 93 • 38 
Carbonate of magnesia 
- 
- 
- 
1*12 
Moisture 
*18 
99*62 
This agrees very nearly with Dr. Hume’s result (see p. 513), 
who found 3*45 of siliceous residue m one sample of Beer Stone. 
Mr. Ekin also analysed some of the hard knotty lumps which 
occur in the zone of Rhynchonella Cuvieri along the coast. He 
notes that this hard chalk was semi-crystalline, while the sur¬ 
rounding chalk had the usual earthy and amorphous appearance. 
The results obtained were as follow : — 
Hard 
1 Soft 
« 
Chalk. 
Chalk. 
Loss on drying at 120 degs. C. - 
- 
- 
- 
3 • 52 
•24 
Carbonate of calcium 
- 
- 
- 
93*5 
95- 
Silica and silicates 
- 
- 
- 
*73 
•78 
Chlorine ----- 
- 
- 
- 
1-228 
*085 
98*978 
96*105 
