SULPHUROUS ACID ON HYPONITRIC ACID. 73 
2: Sulphur iy). te. 27s 
iNatrocen se ais R196 
SOxygenwo wily cr 60:86 
100°00 
The nitrogen was also determined by a second process. A 
quantity of the substance was introduced in a tube previously 
weighed (fig. 3.), which was then bent, drawn out, sealed, and 
=== 
Fig. 3. again weighed. The point 
was after ‘witrda broken,and 
G pure and cold mercury in- 
ry troduced in A B; the ex- 
= tremity of the tube was 
' = then placed under an in- 
= verted jar of mercury, as 
= 
a= x ; 
) represented in the figure. 
Q 
The whole thus arranged, 
the heat of a lamp was ap- 
YW plied to the substance and 
YY a7 Yl, the mercury. These two 
bodies, although without 
action on each athe when cold, react strongly if heated, a mix- 
ture of nitric oxide and sulphurous acid being disengaged. The 
operation is completed by a very slight Bead of tempera- 
ture; sulphate of mercury remaining in the tube. 
The analysis of the gaseous mixture was attempted by several 
processes. Water, potash, borax, and peroxide of lead gave un- 
satisfactory results; this was ascertained by preliminary expe- 
riments, and might have been anticipated after the observations 
of M. Pelouze. Potassium has afforded me better success. In 
a preliminary experiment on a mixture of sulphurous acid and 
nitric oxide in known proportions, very near the corresponding 
volume of nitrogen was obtained. The residue was, however, a 
little too great, depending, perhaps, on some impurity of the 
gases. The following results were obtained by this process :— 
0°501 gramme of substance heated with mercury, afforded 
125°43 cubic centimetres at 21° cent. (70° Fahr.), and under a 
pressure of 0°764 metre; about 4 cubic centimetres more re- 
mained in the little retort, the capacity of which was 5 centi- 
metres. The volume, reduced to 32° Fahr. and 0°76 metre, 
gives 121 cubic centimetres, but these 121 cubic centimetres 
]SSaSSSS= 
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