Dr. Henry's Experiments on Ammonia, &v. 435 
by Berthollet,* who converted 17 measures of ammonia bjr 
electrization, into 33 measures of permanent gas, which is at 
the rate of 194 from 100. Having lately, however, carried 
on the process with the observance of additional precaution, 
(the mercury being first boiled in the tube, before admitting 
the ammonia, and still remaining hot when the gas was passed 
dp), I have obtained from the alkali less than double its vo- 
lume of permanent gas, viz. 280 measures from 155, or at the 
rate of 180,6 from 100. The variableness of the first set of 
results arises, I believe, from the uncertainty of the quantity 
of ammonia decomposed. For if the smallest portion of mois- 
ture remain in the tube, a little ammoniacal gas will be ab- 
sorbed, and will be slowly given out again as the electriza- 
tion goes, on, thus rendering the actual quantity submitted to 
experiment greater than appears. It is probable, also, from a 
fact which I shall afterwards state, that mercury itself, unless 
when heated, may absorb a small portion of alkaline gas. 
The proportion of the hydrogen and nitrogen gases to each 
other in the products of ammonia decomposed by electricity, 
I am satisfied, by recent experiments (June, 1809) is as 
nearly as possible what you have determined, viz. 74 mea- 
sures of hydrogen gas to 2 6 of nitrogen. The nearest ap- 
proximation I have made to these numbers is 73,75 to 26,25. 
Our only method of analyzing mixtures of these two gases, 
(viz. by combustion with a redundancy of oxygen) is not, I 
believe, sufficiently perfect to afford a nearer coincidence. 
The extreme labour and tediousness of the decomposition of 
ammonia by electricity, influenced me to attempt the discovery 
of a shorter and more summary method of analysis. The 
* Journal de Physique, 1786, ii. 176. 
