234 ALKALIES. 



(b.) By furnace heat, the gas being driven through a porcelain tube ; 

 but the decomposition, is in this way very tardy, and requires an in- 

 tense heat to produce a few bubbles of gas.* It is much better done 

 in an iron tube, filled with coils of iron wire, or copper, silver, gold, 

 or platinum; their relative energy corresponds with the order in 

 which they are named above, but iron is by far the most power- 

 ful. The explanation of this decomposition, appears, at first, not 

 very easy ; since the metals do not combine with either of the con- 

 stituents of ammonia, and are not altered. Probably they act by 

 transmitting heat ; the metals neither gain nor lose in weight, and 

 appear to act as conductors only. The result of the experiment 

 gives 3 volumes of hydrogen and 1 of nitrogen gas, in mixture ; 

 electrization gives the same result ; by weight, 17.64 hydrogen, 

 82.35 nitrogen ; as the gases are condensed into half their volume, the 

 specific gravity of ammonia is not that of nitrogen, .9782 + 3 hydro- 

 gen .2083=1.1865, but half of this =.593.f 



A soft, pasty, semi crystallized mass is obtained, when a globule 

 of mercury is galvanized, or a piece of potassium laid, in a cavity, 

 in a solid ammoniacal salt, particularly in muriate of ammonia; 

 it resembles an amalgam, and hence it has been supposed that either 

 hydrogen or nitrogen, or both, has a metallic base ; but the sub- 

 stance has never been obtained isolated, and no satisfactory conclu- 

 sion can be built upon it, 



(c.) By oxygen. 100 measures of ammonia +50 of oxygen, 

 being detonated over mercury in a tube, the oxygen disappears ; 

 then add 30 or 35 measures more of oxygen ; detonate again ; one 

 third of the entire diminution is oxygen, and double this is the hydro- 

 gen ; the nitrogen remains, deducting any that may have been intro- 

 duced with the oxygen gas ; this result corresponds with that under 

 (b.) giving 3 volumes of hydrogen, and 1 of nitrogen, which, as they 

 exist in a state of combination in ammonia, are condensed into 2 vol- 

 umes ; the decomposition of ammonia, therefore, doubles its volume ; 

 it is, however, no longer ammonia, but a mixture of its constituent 

 gases, hydrogen and nitrogen. 



(d.) The mixed hydrogen and nitrogen gases, obtained by igne- 

 ous or electrical decomposition, may be analyzed in the same man- 

 ner, by detonation with oxygen, and will give the same result.} 



* As the ammonia is instantly absorbed by water, none of it will pass through that 

 fluid, and the mixed gases obtained, are of course hydrogen and nitrogen. I have re- 

 peatedly carried this experiment, by the aid of bellows, almost to the fusion of the 

 porcelain tube, without obtaining a cubic inch of gas; while if there be iron in the 

 tube, the gases come over, abundantly. 



t .595 is the number which we have quoted, p. 232 ; Dr. Thomson states it at .590. 



\ The analysis by chlorine is very elegant and easy. See that topic. The chlo- 

 rine removes the hydrogen, and leaves the nitrogen. 



