40 Mr. Davy's Lecture on the Decomposition and Composition 
Now if the corrections for temperature and pressur e be 
made for these estimations, and a mean taken, ico cubic inches 
of ammonia will weigh 18.67 grains, barometer being at 30, 
and thermometer at 6 o° Fahrenheit ; and if the quantity 
used in the experiment of decomposition be calculated upon 
as cubic inches, 60 will weigh 11.2 grains. But the hydro- 
gene gas evolved equal to 80 will weigh 1 .93* grains, and 
the nitrogene equal to 28, -f 8.3. And 11.2, grains — 1.9+ 
8.3 — 10.2. and 11.2 — 10.2. = 1, all the estimations being 
made according to the standard temperature and pressure. 
So that in this experiment on the decomposition of ammonia, 
the weight of the gasses evolved is less by nearly T r T than 
that of the ammonia employed ; and this loss can only be 
ascribed to the existence of oxygene in the alkali ; part of 
which probably combined with the platina wires employed 
for electrization, and part with hydrogene. 
After these ideas the oxygene in ammonia cannot well be 
estimated at less than 7 or 8 parts in the hundred ; and it 
possibly exists in a larger proportion as the gasses evolved 
may contain more water than the gas decomposed, which of 
course would increase their volume and their absolute weight. £ 
In supposing ammonia a triple compound of nitrogene, 
* Lavoisi e r’s Elements, p. 569. A cubical inch of hydrogene is considered as 
weighing .0239. 
+ Researches Chem. and Phil, page 9. From my experiments 100 cubical inches 
of nitrogene weigh at the standard temperature and pressure, 29.6 grains. 
Jin the present state of our knowledge, perfectly correct data for proportions can- 
not probably be gained in any experiments on the decomposition of ammonia, as it 
seems impossible to ascertain the absolute quantity of water in this gas, for electriza- 
tion, according to Dr Henry’s ingenious researches, offers the only means known of 
ascertaining the quantity of water in gasses. 
