452 
SECOND REPORT-I 832 . 
It is very desirable that this important point should be tho¬ 
roughly investigated, as it would appear to throw a shade of 
uncertainty over the densities of the vapours of solid bodies, 
determined by Dumas, which have been adverted to in the 
former part of this Report. 
Simple substances — nan-metallic.—Hydrogen gas .—When 
two volumes of hydrogen and one volume of oxygen are explo¬ 
ded at the ordinary temperature and pressure, the light emitted 
during combustion is very feeble. This fact, with others of a 
similar kind, were brought forward by Davy in confirmation of 
his opinion that the intensity of every flame depended upon the 
presence of solid matter in the state of combustion. But if the 
above mixture of gases be inflamed under a pressure of two at¬ 
mospheres, the light is of the brightest and most vivid charac¬ 
ter, resembling lightning; or in the dark, illuminating a room 
like the sun’s rays, and imparting the well-known phosphores¬ 
cent property to oyster-shells, calcined with sulphur. 
From this fact Dobereiner * infers, that the intensity of light 
depends upon the condensation of the heat by which it is caused. 
But though this may be the true cause of the light emitted in 
the above experiment, it cannot be the source of the great 
light which is produced by introducing certain solid substances 
into flames otherwise scarcely visible. 
Basifying power of hydrogen .—The gaseous compounds of 
hydrogen may be divided into several groups. 
1°. Its compounds with chlorine, bromine, iodine, and fluo¬ 
rine, which all contain in one volume half a volume of hydrogen 
-f half a volume of the radical.—They form a series of strong 
acids, which are decomposed when they combine with the oxi¬ 
dized bases, and form water. Without decomposition they have 
hitherto been combined only with ammonia and pliosphuretted 
hydrogen (N + 3 H and P + 3 H), and with some metallic chlo¬ 
rides, to which they act the part of acids. 
2°. Its compounds with oxygen, sulphur, selenium, and tellu¬ 
rium.—These consist of one volume of hydrogen + half a volume 
of radical, and form a series of weak acids, acting also as bases 
to the stronger acids. Thus, water acts as a base in the liquid 
sulphuric acid, while it is an acid in the hydrates f. 
Like the former group, they form water on combining with 
* Schweigger-Seidel’s Neues Jahrbuch , ii. p. 89. 
f Mitscheriich has shown that the bisulphate of potash may be regarded as a 
double salt — S H-f-S K. Sulpho-naphthalie and sulpho-vinic acids may also 
be so represented; the former being S H + S Na, the latter S H-j-S E; where 
Na denotes naphthaline and E etlierine (4 C+4 H). 
