JMiscellanies. 353 
ids and volatile substances expand by caloric and disperse it, while 
solid bodies resist the repulsive action, and absorb and condense the 
heat so as to become luminous. : . 
But if this view be correct, gaseous substances, disengaged by 
combustion, ought, when forcibly restrained from expansion, to ex- 
hibit incandescence and splendor. - 
An experiment, at once simple and brilliant, confirms the justness 
of this conclusion. 
If a mixture of two volumes of hydrogen and one of oxygen be 
confined in a strong globe of one or two cubic inches in capacity, 
perfectly dry internally, and well closed, and then kindled, it burns 
with as brilliant a light as that of phosphorus in oxygen gas. If the 
detonating gas be compressed into the globe by two atmospheres, it 
emits, when kindled, the splendor of lightning. Even in open day, 
its effect is like that of the most vivid lightning; and by night, it is 
so much like a burst of sun shine, that oyster shells, heated with sul- 
phur, become phosphorescent when exposed to it. If there be moist- 
ure in the globe, or if the cock be left open, the light is very feeble, 
_ because in the first case the light is absorbed by the moisture, and in 
the second, dispersed by the sudden expansion. 
The kindling of the explosive mixture is best effected by the elec- 
tric spark, and the author recommends the apparatus described in 
Singer’s Elements of Electricity, p. 126, fig. 30. The wires of such 
an apparatus should approach the nearer as the gas is more com- 
pressed, for the spark in condensed gases will not pass through so 
great a space. 
These facts induce the author to seek for the cause and condition 
of the brilliancy of fame, not in the presence of solid, incandescent 
matter, but in the forcible accumulation or condensation of caloric, 
and he thinks it not hazarding too much to propose this point of view 
as a photological axiom. He has not examined the luminous effect 
of burning, in this manner, gases, which by combustion with oxygen, 
give permanently elastic products. It is rare to find globes of glass 
strong enough, and of uniform resistance. ‘Tubes are not suitable, 
as they present too large a surface, and consequently absorb too 
much heat.—Idem. 
7. Protoxde of Copper. (Wohler and Liebig.)—The most sim- 
ple and easy method of obtaining protoxide of copper is the follow- 
ing. Dissolve the copper in hydrochloric acid, to which small por- 
