98 EFFECTS of HEAT 
A curious circumftance occurred m one of thefe experi- 
ments, which may hereafter lead to important confequences. 
Some ruft of iron had accidentally found its way into the © 
tube : 10 grains of carbonate were ufed, and a heat of 28° was — 
applied. The tube had no flaw ; but there was a certainty that 
the carbonic acid had efcaped through its pores. When bro- 
ken, the place of the carbonate was found occupied, partly 
by a black flaggy matter, and partly by fphericles of various 
fizes, from that of a fmall pea downwards, of a white fub- 
ftance, which proved to be quicklime; the fphericles being 
interfperfed through the flag, as fpar and agates appear in 
whinftone. The flag had certainly been produced by a mix- 
ture of the iron with the fubftance of the tube ; and the fphe- 
rical form of the quicklime feems to fhew, that the carbonate 
had been in fufion along with the flag, and that they had 
feparated on the efcape of the carbonic acid. 
Tur fubje@ was carried thus far in 1803, when I fhould 
probably have publifhed my experiments, had I not been in- 
duced to profecute the inquiry by certain indications, and 
accidental refults, of amature too irregular and uncertain to 
meet the public eye, but which convinced me, that it was 
poflible to eftablifh, by experiment, the truth of all that was 
hypothetically aflumed in the Huttonian Theory. 
Tue principal object was now to accomplifh the entire fu- 
fion of the carbonate, and to obtain fpar as the refult of that 
fufion, in imitation of what we conceive to have taken place 
in nature. 
Ir was likewife important to acquire the power of retaining 
all the carbonic acid: of the carbonate, both on account of the 
fact itfelf, and'on account)of its confequences ; the refult be- 
ing vifibly mproved by every approach’ towards complete fa- 
turation. . I therefore became anxious to inveftigate the caufe 
of the partial calcinations which had always. taken place, to 
a 
