Compounds of Nitrogen. 509 
by Mr. Dalton to unite with oxygen gas, viz. 
13 nitrous to 10 oxygen, gives the ratio 
in volume of nitrogen to oxygen, in ni- 
tric acid, as 1 to 2.53.(e) M. Gay Lussac 
also, determined by the test of the red sul- 
phate of manganese, which is deprived of 
colour by the nitrous but not by the nitric 
acid, that the latter acid only is generated 
when 134 measures of nitrous gas are made 
to combine with 100 of oxygen, proportions 
which indicate almost exactly 1 volume of 
nitrogen and 2.5 volumes of oxygen in nitric 
acid.(f ) 
But though the synthetic proofs rest on 
such high authorities, and all tend to the 
same point, yet it is desirable to confirm 
evidence of this nature by that of analysis, 
whenever it can be obtained; and the object 
appeared to M. Gay Lussac sufficiently im- 
portant to induce him to seek for this addi- 
tional proof in two different ways, viz. by 
the decomposition of nitrate of lead and also 
of nitrate of baryta, each without addition, 
at high temperatures. The results, however, 
for reasons which he has stated, (same work, 
(e) New System, p. 328, 364. 
(f) Ann. de Chim, et de Phys, i, 404. 
