Effects of Heat modified by Compression. 201 



Some of them continue in a perfect state, though they have 

 been kept, without any precaution, during four or five vears. 

 That set, in particular, remain perfectly entire, which were 

 shown last vear in this society, though some of them were 

 made m 1799, some in 1801 and 1802, and thouoh the first 

 eleven were long soaked in water, in the trials made of their 

 specific gravity. 



A curious circumstance occurred in one of these experi- 

 ments, which may hereafter lead to important consequences. 

 Some rust of iron had accidentally found its way into the 

 lube: ten grains of carbonate were used, and a heat of 28' 

 was applied. The tube had no flaw ; but there was a cer- 

 tainty that the carbonic acid had escaped through its pores. 

 When broken, the place of the carbonate was*found occu" 

 pied, partly by a black slaggy matter, and partly by sphcri- 

 cles of various sizes, from that of a small pea downwards, 

 of a white substance, which proved to be quicklime; the 

 sphericlcs being interspersed through the slag, as spar and 

 agates appear in whinstone. The slag had certainly been 

 produced by a mixture of the iron with the substance of the 

 tube; and the spherical form of the quicklime seems to 

 show that the carbonate had been in fusion along with the 

 slag, and that they had separattfd on the escape of the car- 

 bonic acid. 



The subject was carried thus far in 1603, when I should 

 probably have published my experiments, had I not been 

 induced to prosecute the inquiry by certain indications, and 

 accidental results, of a nature too irregular and uncertain to 

 meet the public eye, but which convinced me that it was 

 possil)le to establish . by experiment, the truth of all that was 

 hypotheticallv assumed in the Iluttonian theory. 



The principal object was now to accomplish the entire 

 fusion of the carbonate, and to obtain spar as the result of 

 that fusion, in imitation of what we conceive to have taken 

 place in nature. 



It was likewise important to acquire the power of retain^ 

 ing all the carbonic acid of the carbonate, both on account 

 of the fact itself, and on account of its consequences; tlve 



result 



