193 
separated elements enter into any new combination. 
In conformity, therefore, with the analogical in- 
ference already deduced (462.), we must suppose 
these chemical rays, like negative electricity, to exert 
an attractive force towards the inflammable element 
of the compound, and a repulsive force towards its 
oxygenous ingredient, whereby, as in electro-chemi- 
cal operations, these elements are separated, and the 
decomposition of the body is effected. Whether, in 
ordinary cases, the calorific rays assist in effecting 
these decompositions, and to what extent they act, 
we have not the means of deciding ; but as the che- 
mical rays, after their separation from the calorific, 
appear to be equally capable (442.) of exerting this 
decomposing power, we must conclude that it is 
chiefly accomplished by those rays alone. 
464. Applying, then, these views to the subject of 
carbonic acid, we have seen that this gas is formed, 
in combustion, by the direct agency (453.) of the 
calorific rays ; and so powerful is the union between 
its elements, that, until the late discovery of potas- 
sium, no single substance, at the ordinary tempera- 
ture of the atmosphere, was capable of effecting their 
separation. At a high temperature, however, Mr 
Cruickshank found that a partial decomposition of 
this acid was accomplished by heating together car- 
bonate of lime and iron-filings, whereby the acid was 
reduced to the state of an oxide *. In the experi- 
ments of Mr Tennant, in which carbonate of lime and 
phosphorus were submitted to a high degree of heat. 
* Nicholson's Journal, 4to, vol. v, p. 4. 
N 
