£Y COMPRESSION. 201 



Another cause of the loss of weight, lay undoubtedly in the Some part was 

 excess of heat employed in most of them, to remove the era- ^^^^ subject"^ut 

 die from the barreU V/ith imllammable substances, no air- of the appara- 

 tube was used, and the heats being low, the air lodged in in- 

 terstices had been sufficient to secure the barrels from de- 

 struction, by the expansion of the liquid metal. In this view, 

 likewise, I often used lead, whose expansion in such low heats, 

 I expected to be less than that of the fusible metal. And the 

 lead requiring to melt it, a heat very near to that of redness, 

 the subject of experiment was thus, on removing the cradle, 

 exposed^in freedom to a temperature which was comparatively 

 high. But, observing that a great loss was thus occasioned, I 

 returned to the use of the fusible metal, together with my 

 former method of melting it, by plunging the barrel, when re- 

 moved from the furnace, into a solution of muriate of lime, 

 by which it could only receive a heat of 250° ot Fahrenheit. 



The effect was remarkable, in the few experiments tried in Obsetvation. 

 this way. The horn did not, as in the other experiments, 

 change to a hard black substance, but acquired a semifluid 

 and viscid consistency, with a yellow-red colour, and a very 

 offensive smell. This shews, that the substances which here 

 occasioned both the colour and smell of the results, had been 

 driven off in the other experiments, by the too great heat ap- 

 plied to the substance, when free from compression. 



I found that the organization of animal substance was en- Sli^^ht heat de- 

 tirely obliterated by a slight action of heat, but that a stronger taiStion*S^ 

 heat was required to perform the entire fusion of vegetable animal matter ; 

 matter. This, however, was accomplished ; and in several ^^Ijf'^.^'^^* 

 experiments, pieces of w'ood were changed to a jet-black and heat, 

 inflammable substance, generally very porous, in which no 

 trace could be discovered of the original organization. In 

 others, the vegetable fibres were still visible, and are forced 

 asunder by large and shining air-bubbles. 



Since the pubhcation of the sketch of my experiments, I S bstances 

 have, had the pleasure to read Mr. Hatchett's very interesting f/"**?"^!^^ 



\ . Mr. Hatchett 



account of various natural substances, nearly allied to coal ; and elucidated 



and I could not help being struck with the resemblance which ^y^^^^'^ ^^P^' 

 ^ = iiments, 



my results bear to them, through all their varieties, as brought 



into view by that able chemist ; that resemblance affording a 



Vol. XIV.— July, 180&* Dd pre- 



