LOWER CHALK—CHEMICAL COMPOSITION. 
341 
high part of the Lower Chalk. The analysis was made by Mr. 
D. Forbes.* The second is an analysis of grey chalk from 
Snodland, quoted by Mr. J. L. Spoor.+ 
1. 
2. 
Insoluble siliceous matter - 
* 
3-61 
6-84 
Calcium carbonate- 
- - 
- 
- 
94*09 
8V35 
Magnesium carbonate - 
- 
- 
- 
•31 
— 
Alumina - 
- 
- 
■ - 
— 
1-14 
Oxides of iron - 
- 
- 
- 
— 
•38 
Alkalis - - - 
- 
- 
- 
— 
4-29 
Sodium chloride - 
- 
- 
- 
1-29 
—. 
Water ----- 
*70 
— 
100-00 
100-00 
It will be seen that the quantity of free quartz in these samples is very 
small, and that the greater part of the silica must be in combination with 
the Alumina as clay. 
Of the beds forming the zone of Offaster sphcericus in Lincoln¬ 
shire four analyses have been made and are given below. They 
include two of pink chalk (from the lower and the upper band) 
one of yellow chalk and one of a hard grey chalk occurring between 
the two pink bands. All the samples came from Louth, and were 
published in the Survey Memoir on East Lincolnshire. The first 
three analyses were made by Mr. Meaburn Stainland in the Labora¬ 
tory of the School of Mines, London, and the fourth by Mr. Grant 
Wilson at Edinburgh. 
Lower 
Pink 
Band. 
Upper 
Pink 
Band. 
Yellow 
Chalk in 
Upper 
Pink 
Band. 
Hard 
Grey 
Chalk. 
Insoluble Portion. 
Silica ----- 
Alumina and peroxide of iron 
10-80 
1*10 
j- 2*10 
4-96 
5-26 
1-57 
Loss on ignition - 
— 
— 
. — 
1-19 
Soluble Portion. 
Lime ----- 
45*91 
53*62 
51-72 
48-89 
Carbonic acid 
36-51 
42-86 
40-91 
38-51 
Phosphoric acid - 
trace 
trace 
— 
•29 
Magnesia ----- 
•71 
•36 
*92 
•73 
Alumina ----- 
1 *35 
— . 
trace 
•31 
Peroxide of iron - 
1 -03 
•35 
1 -05 
1 *107 
Oxide of manganese - 
— 
— 
— 
M5 
Water ----- 
1 -92 
•75 
1 • 20 
1 *64 
99-33 
100-04 
100-76 
99 * 64 
* See Quart. Journ. Geol. Soc., Vol. xxvii. p. xlix. 
+ Official Local Guide, Industr. Sec. (1889), p. 215. 
I Stated to be protoxide of iron. 
z 2 
4219. 
