A HARD-WORKING DIET. 13 
there is nothing to be seen, but if we raise the tem- Oxidation of 
Carbon and 
perature by applying a highly heated wire or a Hydrogen 
light the Carbon and Hydrogen both begin to unite dea ted he 
with the Oxygen of the air and “burn.” Hydrogen ea 
and Oxygen when combined form Hydrogen-Oxide or 
“water,” as mentioned before, and, if a plate or any- 
thing cool be held over the flame, drops of water 
can be collected. The Carbon which thus loses its 
companion Hydrogen, and has zof united with the 
Oxygen of the air, can be collected in a solid form, 
and, indeed, smuts and smoke are small particles of it. 
It has travelled through the pipes, however, as a gas. 
The Carbon which does unite with Oxygen forms car- 
bonic acid, with which everybody may be familiar 
(though it is a gas which cannot be seen), and a test 
for its presence is given below. Thus from the gas there 
is obtained by “splitting up” by heat, a solid (carbon), 
a liquid (water), ‘and a gas of totally different composi- ee 
tion (carbonic acid). This isa rough chemical analysis. analysis. 
The same results can be obtained from an oil lamp 
where the Carbon and Hydrogen are present as fluid, 
or from acandle where the Hydrogen and Carbon are 
present as solid. 
The water and carbonic acid can be collected most 
conveniently, perhaps from a candle, as the experiment 
can be made ona table. For observing the formation 
of the water it will be an advantage to support the 
plate slightly tipped on one side as the drops will run 
together, and also to keep the plate cool by putting . 
cold water in it. The fact of being able to collect solid 
Carbon is mentioned for the sake of the illustration of 
an element being present in a compound without its 
being recognised till it is separated out. It can only 
