XXIII. Account of a substance found in a clay-pit; and of the effect of the Mere of Diss, upon various substances immersed in it. By Mr. Benjamin Wiseman, of Diss, in Norfolk. Communicated by John Frere, Esq. F. R. S. With an analysis of the water of the said Mere. By Charles Hatchett, Esq. F. R. S. In a letter to the Right Hon. Sir Joseph Banks, Bart. K. B. P. R. S
The substance I have inclosed was found near Diss, in a body of clay, from five to eight feet below the surface of the soil. All the pieces I observed laid nearly in a horizontal direction; and varied in size, from two or three ounces, to as many pounds. The colour of the substance, when taken fresh from the clay-pit, was like that of chocolate; it cuts easily, and has the striated appearance of rotten wood. The pieces were of no particular form; in general, they were broad and flat, but I do not recollect to have met with a piece that was more than two inches in thickness: it breaks into laminæ, between which are the remains of various kinds of shells. The specific gravity of this substance, dried in the shade, is 1.588; it burns freely, giving out a great quantity of smoke, with a strong sulphureous smell. By a chemical analysis, which I cannot consider as very accurate, one hundred grains appear to contain, Of inflammable matter, including the small quantity grains of water contained in the substance - - - - - 41.3 Of mild calcareous earth - - - - - - - - - 20.0 Of iron - - - - - - - - - - - - - 2.0 Of earth, that appears to be silex - - - - - - - 36.7 ¯¯¯¯¯¯¯ 100