15 
of certain inflammable gaseous compounds. 
one gasometer to the other for about a quarter of an hour. 
The apparatus having cooled, the gas was found to have sus- 
tained an increase of volume = 40 parts ; it burned with the 
pale flame of hydrogen; and when detonated over mercury 
required scarcely more than half its volume of oxygen, and 
afforded a very minute portion of carbonic acid. The interior 
of the platinum tube was lined with charcoal, the crystals 
were covered with it, and some had assumed a beautiful 
brown tint. 
4. The conclusions drawn from the last experiment are 
founded upon the supposition, that olefiant gas is decomposed 
by the simple operation of a high temperature, and that one 
volume is resolved into two volumes of hydrogen, losing at 
the same time its carbon. The importance of this fact, as con- 
nected with these researches, induced me to repeat with every 
requisite precaution, the beautiful experiment of M. Ber- 
thollet, which consists in decomposing this gas by passing 
it repeatedly through a red hot earthen tube; instead of 
which, however, I employed a tube of platinum, arranged as 
in the last experiment, increasing the heated surface by the 
introduction of quartz crystals. One hundred measures of 
olefiant gas,* obtained by distilling alcohol with sulphuric 
acid, were passed and repassed through the tube heated to 
high redness, until they ceased to dilate : when the apparatus 
was cool, the volume of gas was almost exactly doubled ; 
there was a copious deposition of charcoal in the part of the 
tube that had been ignited, and the evolved hydrogen was so 
* This gas was washed with solution of potassa to separate a little carbonic acid, 
and was then ascertained to be pure by the action of chlorine, with the precautions 
afterwards described. 
