185 
while, at the positive pole, decomposition and com* 
bination successively take place, according to the na- 
ture of the bodies employed, and the intensity with 
which the electric matter is made to act, 
453. After thus tracing the operation of the dif- 
ferent electricities, in promoting the chemical actions 
of decomposition and combination, let us pass to the 
consideration of those, which the calorific and che- 
mical rays of the solar beam are respectively found to 
produce. It is known, that, by concentrating the so- 
lar rays upon any body, a most intense heat is pro- 
duced ; that metals are converted into oxides ; that 
the diamond or charcoal is made to combine with 
oxygen, and form carbonic acid ; and, in fact, that 
almost all the combinations, which can be effected 
by combustion, may be, in this manner, accomplish- 
ed. Now the portion of solar light which contri- 
butes to these effects, must be the calorific rays ; for 
neither the illuminating, nor the chemical rays pro-? 
duce heat, and they are, consequently, incapable of 
exciting combustion. 
454. But these same calorific rays, not only thus 
cause the combination of oxygen with bodies, but, 
under different circumstances, they occasion the sepa- 
ration of this element from them, Thus, if a com- 
pound combustible be exposed to the concentrated 
action of the solar rays, its several elements are first 
separated, and almost, at the same instant, recombine 
into a new form, according to the nature of the body 
employed, and the greater or less intensky with 
which the caloric is made to act j and hence the va- 
rious gaseous, fluid, and solid products, which the 
