RADIATION OF HEAT BY G-ASEOUS AND LIQUID MATTER. 
225 
Table LI. 
Name of liquid. 
Bisulphide of carbon 
„ „ saturated with sulphur 
„ „ „ with iodine . 
Bromine 
Chloroform . 
Iodide of methyl 
Benzole 
Iodide of ethyl 
Amylene 
Sulphuric ether 
Acetic ether 
Formic ether 
Alcohol 
Water saturated with rock-salt 
Transmission in hundredths 
of the radiation. 
... 83 
... 82 
... 81 
... 77 
... 73 
... 69 
... 60 
... 57 
... 50 
... 41 
... 34 
... 33 
. . . 30 
... 26 
These results are but approximate, but they are not very far from the truth ; and it 
is impossible to regard them without feeling how purely the act of absorption is a 
molecular act, and that when a liquid is a powerful absorber the vapour of that liquid 
is sure also to be a powerful absorber. 
To experiment with water, it was necessary to saturate it with the salt of which the 
cell was formed, but the absorptive energy is due solely to the water. We might infer 
from this alone, were no experiments made on the aqueous vapour of the atmosphere, 
that that vapour must exert a powerful action upon terrestrial radiation. In fact, in all 
the statements that I have hitherto made I have underrated its action. 
The deportment of the elements sulphur and iodine, dissolved in bisulphide of carbon, 
is in striking harmony with all that we have hitherto discovered regarding the action of 
elementary bodies. The saturation of the bisulphide by sulphur scarcely affects the 
transmission, while a quantity of iodine sufficient to convert the liquid from one of 
perfect transparency to one of almost perfect opacity to light, produces a diminution of 
only two per cent, of the radiation. This shows that the heat really used in these expe- 
riments consists almost wholly of the obscure rays of the lamp. It is worth remarking 
that the obscure rays of a luminous source have a much greater power of penetration in 
the case of the liquids here examined than the rays from an obscure source, however 
close to incandescence. The deportment of bromine is also very instructive. The liquid 
is very dense, and so opaque as to cut off the luminous rays of the lamps, till it transmits 
77 per cent, of the total radiation. It stands in point of diathermancy above every com- 
pound liquid in the list except bisulphide of carbon. This latter substance is the rock- 
salt of liquids. 
Before a strict comparison can be made between vapours and liquids, they must be 
examined by heat of the same quality, and I have already made arrangements with 
which I hope to obtain more complete and accurate results than those above recorded. 
