11, York Place, | Portman Square, | London. W.
1 March 1872
Dear Mr Darwin
As you know that I rather pride myself on being systematic—I was annoyed today that I could not at once lay my hands on the analyses of chalk, I found them the moment you left1—the difficulty in doing so before being because I had entered them under the head of investigations of the Atlantic mud2
I enclose herewith the results of 2 analyses which you can take as representatives only to show the components of the true chalk which contains the flints—and of the most impure or grey chalk (chalk marl)—lowest in the series
Yours very truly | David Forbes
| White chalk– with flints | |||
| Shoreham | |||
| Carbonate of Lime – | 98·40 | ||
| — of Magnesia | 0·08 | ||
| Insoluble (silicious rock debris) | 1·10 | ||
| Alumina(with Phosporic acid | 0·42 | ||
| 100·00 | |||
| Grey chalk. beds resting on greensand | |||
| level of low water Folkestone | |||
| Carbonate of lime | 94·09 | ||
| — of Magnesium | 0·31 | ||
| Insoluble (rock debris) | 3·61 | ||
| Phosphoric acid | traces | ||
| Sea | } | Chloride of sodium | 1·29 |
| infiltration | |||
| Water | 0·70 | ||
| 100·00 | |||
Please cite as “DCP-LETT-8233,” in Ɛpsilon: The Charles Darwin Collection accessed on