A HARD-WORKING DIET. 7 
produce light. But it is hardly in accordance with the 
popular use of the word to speak of an iron nail which 
is rusting in the damp as “burning.” There is this 
more serious objection to employing the more familiar 
word “burning ” instead of “oxidation.” People have 
lately dropped into the habit of speaking of an electric 
incandescent arc lamp as “burning” steadily or badly, 
though this light does not depend on oxidation at “ Oxidation” 
all. “Burning” is then not always ivalent for equ ae 
j = ys an equivalent 10PF equivalent to 
“ oxidation.” burning.” 
It is desirable to have a clear mutual understanding 
about the use of this word “ oxidation,” as it will have 
to be frequently used in the following pages. Ovxida- 
tion is the act of combining with Oxygen. All the 
elements except Fluorine combine with Oxygen. The Oxygen is 
a : . ‘* free”? in the 
Oxygen may come from the air of which, as mentioned, air and in 
combination 
in many 
compounds, 
it forms one-fifth by weight ; it may come from water 
of which it forms eight-ninths by weight ; it may come 
from nitre of which it forms nearly one-half by weight 
(for which reason it is used in making gunpowder) ; it 
may come from chlorate of potash of which it forms 
two-fifths by weight, or permanganate of potash 
(Condy’s fluid) or from many other compounds. The 
combination may be rapid as in the case of gas- 
burning, or slow as in the case of the “tarnishing ” of 
kitchen coppers ; it may give rise to but little heat or 
to dazzling light. In any case the combination with Oxidation, 
oxygen is called oxidation, and OXIDATION, it seems, pie ee 
ALWAYS GIVES RISE TO HEAT. The way in which ™S¢ ' be 
our life depends on this is spoken of on p. 17, &c. 
CARBON is perhaps generally felt to be more fami- Carbon. 
liar than Oxygen as it can be seen. Fine particles 
of it are a solace to the eyes of a weary man as 
D 
