318 
A mixture of two parts of quicklime and 
one of hydrate of soda is an ge by slaking 
some well-burned lime with the necessary 
quantity of a solution of soda; the whole is 
evaporated to dryness, ignited, the dry mass 
pulverized as quickly as possible, and then 
transferred to well-stopped bottles, in order to 
exclude carbonic acid and moisture. When an 
analysis is to be made we proceed as usual, 
making the mixture in a warm mortar, only 
substituting the alkalized lime for oxide of 
copper; the accidental presence of a little 
moisture, after the weight of material for ana- 
lysis is accurately known, is of no consequence 
in this case. Ae 
Having introduced the mixture, it is better 
loosely to plug the aperture of the retort with a 
few fibres of asbestus (which has been ignited 
just before) to prevent any mechanical trans- 
port of the mixture into the apparatus through 
which the gases are passed ; on applying heat 
to the combustion-tube in the ordinary way, 
and with the usual precautions, the substance 
is decomposed, and the whole of the nitrogen 
escapes as ammoniae The drying tube and 
potash apparatus are dispensed with, and the 
Fig. 431. 
ce 
d d 
A.—a, mouth of the combustion-tube ; 5, three- 
legged brass tube furnished with the stop-cock 
(c); d, d, caoutchoue connectors; e, glass tube, 
upwards of 30 inches long, recurved at the lower 
extremity for delivering gas in the mercurial 
trough. 
B.—Bulb-tube for containing hydrochloric acid 
in the determination of nitrogen by the method of 
Varrentrapp and Will, 
.—a, mouth of the combustion-tube; 8}, 
caoutchouc connector ; c, gas delivering tube. 
ammonia is collected by attaching a bulb-tube of 
the form represented (fig. 431, B), air-tight with 
a good cork, to the retort-tube, the apparatus 
having been previously charged with hydro- 
chloric acid sp. gr. 1.1, as high as the lines in 
ORGANIC ANALYSIS. 
the figures indicate. Pure hydrochloric acid. 
is easily procured for this purpose by diluting: 
the ordinary acid of the shops till it has a 
sp. gr. of 1.1, and distilling in glass ves- 
sels—the first eighth may be rejected. Dis- 
ullation may be proceeded with until three- 
quarters of the acid employed have passed 
over. It is better for the operator always to 
rectify his own acid, in order to be quite 
sure of the absence of any trace of aim- 
monia. The tube connecting the bulbs should 
be somewhat larger in diameter than that of the 
ordinary Lage apparatus, in order to allow — 
the liquid to be poured out readily. When — 
the operation is complete, absorption will take — 
place and the fluid rise in the bulb nearest the 
fire; at this moment we nip off the top of the 
combustion-tube and draw air carefull — 
the apparatus in the usual way. When 
a is terminated, ie of the 
ulb-tube are emptied into a evaporating — 
dish, and the hopieaak washed out first with a 
little alcohol and ether, and afterwards several 
times with water; some solution of bichloride 
of platinum is added, and the whole do 
to dryness by a water-bath or chloride of cal- 
cium bath; when dry, it is digested with a 
mixture of two parts of alcohol, sp. gr. & 
and one of ether, which dissolves the excess 
bichloride of platinum, and leaves the doubl 
chloride of platinum and ammonium in a crys= 
talline form. 7 
This must now be brought upon a weighed 
filter, (or better, upon two rd of hich 
has been counterpoised against the other,) am 
washed repeatedly with the mixture v0 
parts of alcohol and one of ether until noth 
further is taken up; the precipitate and filte 
must be dried by a water heat and the weigh’ 
accurately observed. According to Va 
and Will, 220.52 grs. of the ammonia-chlori 
are equivalent to 14 grs. of nitrogen; the est 
mate of these writers is too high, and 225 grs. ar 
more nearly equal to one equivalent or 14 
of nitrogen. Practically, however, their ¢: 
lation is very near the truth, as during 
operation a minute quantity of hydrochlorat 
of ammonia escapes uncondensed, and the tw 
errors compensate each other. 4 
This method of determining nitrogen ai 
swers for all cases excepting those in whi 
occurs in the form of nitric acid, when it m 
be determined by volume and its weight the 
deduced. For this purpose the proces 
Dumas is the most trustworthy. A retort 
of about twenty inches long is em > 
drawn out into a tail, but sealed with a roun 
extremity; about two inches of the tube 
filled with carbonate of oe or of lead, 
then the mixture with oxide of copper a 
and covered as usual with a layer of | 
oxide; beyond this the last two or three im 
of the tube are filled with clean coppert 
ings, as already directed, to decompose ai 
the oxides of nitrogen which may orn 
The retort tube is then connected with a th 
legged apparatus of brass or copper (fig. 4: 
b), one limb of which is furnished i 5 
cock (c). The connection with the ret 
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