104 



EFFECTS Oy BEAT. 



Horn totally vo» 

 latilized under 

 ftrong but not 

 extreme pref- 

 fure. 



Exhibition and 

 4efcription of 

 the refults of 

 carbonate ex- 

 pofed to heat 

 under ftrong 

 preffurc. 



ceive that the coal which now remains In the world is but a 

 fmall portion of the organic matter originally depofited, the 

 mod volatile parts having been driven off by the a6lion of heat 

 before the temperature had rifen high enough to bring the fur- 

 rounding fubftance into fufion, fo as to confine the elaftic fluids 

 and fubjeft them to compreflion. 



In feveral of thefe experiments, I found that when the pref- 

 fure was not great, when equal, for inftance, only to 80 at- 

 mofpheres, that the horn employed wasdiffipated entirely, the 

 glafs tube which had contained it being left almoft clean, yet 

 undoubtedly if expofed to heat without compreflion, and pro- 

 teded from the contact of theatmofphere, the horn would leave 

 a cinder or coak behind it, .of matter wholly devoid of volati- 

 lity. Here then it would feem as if the moderate preffure, by 

 keeping the elements of the fubftance together, had promoted 

 the general volatility, without being ftrong enouglj to refill 

 that expanfive force, and thus, that the whole had efcaped. 

 This refult, which I fhould certainly not have forefeen in the- 

 ory, may perhaps account for the abfence of coal in Situations 

 where its prefence might be expefled on principles of general 

 analogy. 



I have fhewn feveral fpecimens of thefe refults to my friends, 

 in particular to Lord Webb Seymour, Mr. Play fair, and Mr. 

 Davy, who have agreed in thinking that the inveftigation is 

 now brought to fuch a flage of advancement, that the refult 

 ought to be made public. 



I propofe in the courfe of next winter to lay before the So- 

 ciety a particular account of all thefe refults, and of the me- 

 thods followed in obtaining them. In the mean time I fliall 

 now fubmit a few of them to the infpe^ion of the gentlemen 

 pre fen t. 



Nos. 1, 2, 3, 4, 5, 6 and 7, were all produced in feparate 

 experiments from pounded carbonate of lime. No. 1, was 

 amongfl the firft of myfuccefsful refults, having been obtained 

 in 1799. It is a firm (lone, requifing a fmart blow of a ham- 

 mer to break it. It was inclofed in a cartridge of paper, the 

 mark of which it ftill bears. The other fix are Hill harder and 

 more compaft, approaching nearly in thefe qualities to com- 

 mon lime-ftone. Nos. 2, 4, and 7, poflefs a degree of femi- 

 tranfparency moft remarkable in No. 4, and all of thefe fpeci* 

 mens exhibit an uneven fraflure, approaching to that of bees- 

 wax 



