DETERMINATION OF NITROGEN. 
149 
the contents of the bulb by heat applied to the posterior 
part : it is thus spread throughout the middle of the tube, 
without being suddenly decomposed ; and if the heat be 
gradually carried backward it is easy to effect a uniform dis- 
engagement of gas. 
x\fter the combustion is terminated, and air by inspiration 
has traversed the whole of the apparatus, the contents of the 
apparatus of absorption is to be discharged through the tube 
g into a small porcelain capsule. By the aid of a washing 
bottle, a small quantity of a mixture of alcohol and ether is 
to be thrown into the apparatus, and brought in contact suc- 
cessively with every portion of the bulb ; this liquor is then 
added to the acid containing the hydrochlorate of ammonia, 
and washings with water continued until they no longer ex- 
hibit an acid reaction. The first washing with alcohol is 
with the view of dissolving the hydro-carburet, which 
is sometimes found, and which prevents the interior of the 
bulbs being completely washed by the water. It is rarely 
necessary to tfse more than thirty to forty-five grammes, 
(450 to 675 grs.) of liquid to carry off all the hydrochlorate 
of ammonia of the apparatus. 
There is then to be added to the liquid containing this salt, 
an excess of solution of pure chloride of platinum, and the 
whole evaporated to dryness, on a salt water bath heated by a 
spirit lamp, and moreover, completely protected from the 
dust. When the combustion has been well conducted the 
dry hydrochlorate of platinum and ammonia will always have 
a fine yellow color ; if the matter was very rich in carbon or 
difficult to burn, the hydrochlorate of ammonia and platinum 
possesses a deeper color, because the hydrochloric acid in 
contact with the carburetted hydrogen blackens it ; this co- 
lor, however, has no influence on the result, provided it be 
carefully washed. 
To the dry residue in the porcelain capsule, when cold, a 
mixture of two volumes of alcohol and one of ether is to be 
added, in which the hydrochlorate of ammonia and pla- 
