Complete 
oxidation of 
Carbon 
always gives 
rise to Car- 
bonic acid. 
Hydrogen. 
Nitrogen. 
8 ON THE PLACE OF PISHAN 
he watches them in a beam of sunlight curling slowly 
upwards from his pipe, and, rolling gently into lazy 
folds, linger over him with an air of tranquillity and 
rest. 
Larger particles of it are the terror of the laundry- 
maid as she sees them settling on the linen she has 
carefully washed to such dainty whiteness. 
Carbon, too, makes the fortune of the chimney-sweep 
(whose occupation the Smoke Abatement Committee 
are trying to abolish), and his sack is valued by many. 
Under the name “black lead,” which contains no 
lead at all, it is used for drawing-pencils, and it is met 
with in its purest form in the diamond. 
Mixed with small quantities of other things Car- 
bon forms the bulk of coal, charcoal and wood. 
Fine heated particles of it are the source of light of . 
ordinary flames. 
The union of Carbon with Oxygen forms invisible 
gases, and THE COMPLETE OXIDATION OF CARBON 
ALWAYS PRODUCES CARBONIC ACID, an invisible gas 
of which more will be presently said. 
HYDROGEN is a gas which occurs naturally in com- 
bination with some other element, and when it is 
wanted for use (as for the oxy-hydrogen light) or for 
the purpose of examining it, some compound con- 
taining it is “split up” so that the hydrogen is set 
free. The compound usually chosen for this purpose 
is Hydrogen-Oxide, commonly called water (see 
Pp. 9). 
NITROGEN, like Oxygen, occurs free (that is, not 
as a compound) in the air. It also forms many com- 
pounds, of which two familiar ones are nitrous oxide 
(laughing gas) and nitre (saltpetre.) 
