Letter 4553

Sir,-I wrote a pretty while ago to you about the

Hockesdon earth, which, because I fear it miscarried, I now repeat, desiring your opinion of it.

Not far from Moorfields, near the new square in

Hockesdon, some workmen digging a cellar for a new house in the end of a garden, when they were about three feet below the surface of the ground, found a very strong smell in the one half thereof. Passing that way, and finding it very surprising, and a thing that I had neither heard of nor seen before, I thought it worth farther enquiry.

The workmen having dug a pit about six feet deep,

at about three yards’ distance from that end of the cellar which smelt so strong, I there found three several layers of earth one over another, all of them, more or less, having the same scent. The uppermost stratum was clay, or, as the workmen call it, loom. It did not smell till three feet deep, but then was very strong, and some- thing noisome. If one look earnestly on some pieces of this clay, there are easily discernible several small quan- tities of a bituminous substance, brownish colour, and tough consistence. I doubt not but this substance gives the smell and other qualities to this layer. This clay preserves its scent a pretty while, though by degrees it grows fainter; and being exposed to the air for about a month, will lose it quite. Eight pounds of this clay dis- tilled in a retort, placed in a sand-fire (third degree of heat), yielded one pound of phlegmatic liquor, and six drachms of oil, of a quite different smell from anything I have hitherto met with.

The second layer was gravel, which reached from three

and a half to about four and a half deep, or thereabouts. It very much resembles the other in all its qualities, ex- cept the noisomeness of its smell. It loses its scent much sooner than the former.

The third layer was an earthy sand, which smells

stronger than the other two, and withal is much more fragrant. The deeper you dig it smells the stronger. I took eight pounds of this layer, at nine feet deep, and filled a retort with it, and placed it as the clay; but it afforded only six ounces of phlegmatic liquor, and two drachms of oil. This sandy loose earth quits its scent in about a fortnight, being exposed to the summer air.

Considering that waters owe their greatest differences

to the several soils through which they pass, I was very desirous to see what sort of waters would be produced by their being percolated through such a strainer as this strange sort of earth; and desiring the owner to dig till he should find water, he accordingly did; and when he came to about eighteen feet deep, water came in very plentifully, conditioned as follows: –

It had at top a curiously coloured film, the colours of

it resembling those of the rainbow. Under this was a whitish-coloured water, which, upon standing in a phial some days, lets fall a brownish sediment, and by that means becomes diaphanous. It smelt very strong, as the earth did; was somewhat bitter and clammy, as one may see by putting his hands in it, and suffering them to dry without wiping. If you put some powdered galls into a glass of this water, so soon, or a little after, you take it out of the well, it will turn of a purplish red; but if it stand a day or two, it will not at all.

Several persons having drunk of this well, about three

pints, say that usually it works about three times by stool, and very much by urine.

From which I conclude it to be a natural bitumen,

perhaps sui generis, that impregnates both water and earth. I desire your opinion on it, and remain, &c.

London, November 10, 1685.