14 Effects of Heat modified by Compression. 



compressor, in which a very low red heat had been ap- 

 plied, that the carbonate lost one or one and a half per cent. 

 Now, as this must have happened in a temperature scarcely 

 capable of inflaming gunpowder, it is clear that such loss 

 would not have been prevented by its presence ; whereas 

 water, beginning far below redness to assume a gaseous 

 form, will effectually resist any calcination, in low as well as 

 in high heats. And as the quantity of water can very easily 

 be regulated by weight, its employment for this purpose 

 seems liable to no objection. 



On the 2d of January 1804, I made an experiment with 

 marble and chalk, with the addition of J»l grain of water. 

 I aimed at a low heat, and the pyrometer, though a little 

 broken, seemed clearly to indicate 22°. Unluckily, the muz- 

 zle of the large tube, which was closed as usual with chalk, 

 was placed uppermost, and exposed to the strongest heat. 

 I found it rounded by fusion, and in a frothy state. The. 

 little tube came out very clean, and was so nearly of the. 

 same weight as when put in, that its contents had lost but 

 0*074 per cent, of the weight of the original carbonate. The 

 marble was but feebly agglutinated, but the chalk was in a 

 state of firm limestone, though it must have undergone a 

 heat under 22°, or that of melting silver. This experiment 

 is certainly a most remarkable one, since a heat has been 

 applied in which the chalk has been changed to hard lime- 

 stone with a loss less than the lOOOdth part of its weight 

 (exactly ■ 1 ^ 1 _ , .) ; while, under the same circumstances of pres- 

 sure, though probably with more heat, some, of the same 

 substance had been brought to fusion. What loss of weight 

 this fused part sustained, cannot be known. 



On the 4th of January a similar experiment was made 

 likewise with 1*1 grain of water. The discharge of the me- 

 tal was accompanied with a flash of flame. The pyrometer 

 indicated 86*. The little tube came out quite clean. Its 

 contents had been reduced from 14-.73 to )4 - 4G; difference 

 0*07 grains; being 0-47 per cent, on the original carbonate, 

 less than l-2C0dth part of the original weight (exactly ^J-^-). 

 The chalk was in a state of firm saline marble, but with no 

 unusual qualities. 



These 



