116 MEMOIR OF THE LATE DR. HENRY. 
disturbed by the production of nitrate of am- 
monia. In estimating the proportion of hydro- 
gen and nitrogen constituting ammonia, he 
obtained somewhat less hydrogen than the theo- 
retical quantity, a deficiency which he rightly 
ascribed to the cooling agency of so large a 
volume of azote causing a part of the hydrogen 
to escape unburned. He afterwards by employ- 
ing nitrous oxide instead of oxygen, obtained 
and published in the Memoirs of this society, 
results that establish precise multiple relations. 
The gaseous substances, issuing from the 
destructive distillation of coal and oil, had very 
early engaged Dr. Henry’s attention, and he 
had at various times devoted much labour both 
to their chemical analysis and to ascertain their 
respective fitness for the purposes of illumina- 
tion. The general conclusions, which he had 
made known in several successive memoirs, 
were that these gaseous products are mixtures 
of olefiant, carbonic oxide, carburetted hydrogen 
and hydrogen gases in varying proportions, 
with other accidental impurities, as carbonic 
acid and sulphuretted hydrogen. An opposite 
doctrine had been proposed to the Royal Soci- 
ety by a distinguished chemist. It was main- 
tained, that carburetted hydrogen does not 
