of certain hiflammable gaseous compounds. 21 
carbonic acid ; and that no other definite compound of carbon 
and hydrogen can be recognised in them, except olefiant 
gas. 
SECTION II. 
Comparative experiments on the illuminating and heating powers 
of olefant, coal, and oil gases , and on some general properties 
of radiant matter. 
1. In the following experiments I employed a gasometer 
with counterpoise weights acting over regulating pullies, and 
capable of containing about 5000 cubical inches, or about 
2,89 cubical feet: the different jets were attached to it in 
the usual way, and the pressure was measured by the differ- 
ence in the level of the water within and without the bell, to 
which was attached an accurately graduated scale sliding 
through the frame of support. 
2. Having filled this gasometer with pure olefiant gas, it 
was allowed to issue from a brass jet having a single perfo- 
ration of -g 1 ^ of an inch diameter, under a pressure of a half 
inch column of water; it was then inflamed, and regulated 
by means of a stopcock, so as to produce a light equal to 
that of a wax candle burning with full brilliancy ; the relative 
intensity of the light of these flames was ascertained by a 
comparison of shadows. Under these circumstances, the 
consumption of gas was found = 64,0 cubical inches per 
hour, or 0,3 7 cubical feet. When the same burner was used 
with oil gas, it consumed 800 cubical inches per hour, or 
= 0,47 cubical feet. 
3. I now employed an Argand burner, with a cylindrical 
glass, constructed in the usual way, with 12 holes each of the 
