I2 4 EFFECTS of HEAT 



experiments, a confiderable additional fufibility has been com- 

 municated to the carbonate. 



These experiments, and many others made about the fame 

 time, with the fame fuccefs, clearly prove the efficacy of wa- 

 ter in aflifting the compreflion ', and refults approaching to thefe 

 in quality, obtained, in fome cafes, by means of a very fmall air- 

 tube, mew that the influence of water on this occafion has 

 been merely mechanical. 



During the following fummer and autumn 1803, I was oc- 

 cupied with a different branch of this fubjed, which I mail 

 foon have occaiion to mention. 



In the early part of lafl year, 1804, I again refumed the fort 

 of experiments lately defcribed, having in view principally 

 to accomplifti abfolute compreflion, in complete imitation of 

 the natural procefs. In this purfuit, I did not confine myfelf 

 to water, but made ufe of various other volatile fubftances, 

 in order to affift compreflion ; namely, carbonate of ammo- 

 nia, nitrate of ammonia, gunpowder, and paper impregna- 

 ted with nitre. With thefe I obtained fome good refults, but 

 none fuch as to induce me to prefer any of thefe compreflbrs 

 to water. Indeed, I am convinced, that water is fuperior to 

 them all. I found, in feveral experiments, made with a Ample 

 air-tube, without any artificial compreflbr, in which a very 

 low red-heat had been applied, that the carbonate loft one or 

 one and a half per cent. Now, as this mufl have happened in 

 a temperature fcarcely capable of inflaming gunpowder, it is 

 clear, that fuch lofs would not have been prevented by its pre- 

 fence : whereas water, beginning far below rednefs to aflume 

 a gafeous form, will effectually refift any calcination, in low 

 as well as in high heats. And as the quantity of water can 

 very eaiily be regulated by weight, its employment for this 

 purpofe feems liable to no objection. 



On 



