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was made, and the outer crust being removedby a knife, some of the inner part was taken upby a dry iron spoon, and put into a very dryglass tube inverted over mercury that had justbeen boiled. The tube being closed with adry stopper was gently shaken, the amalgamwas speedily decomposed, and a considerablequantity of gas was generated, consisting ofammonia and hydrogen in the proportion ofabout 2) to 1. The authors say that it is im-possible that any moisture should here be pre-sent, since this is incompatible with potassium,and hence it appears that the amalgam cannotcontain any basis of ammonia (supposing thealkali itself to be an oxyd of some unknownbasis) since there is no obvious source fromwhich this basis could abstract oxygen when theammonia is regenerated. The authors endea-voured to ascertain the respective quantities ofammonia and of hydrogen given out during thedecomposition of the amalgam, and they foundthat the mercury of the amalgam gave about3.47 times its volume of hydrogen, and 4.22of ammonia, which together made -j-o/utro ofthe weight of the mercury.
On the action of Potassium on Ammonia.
When potassium is fused in ammoniacalgas, s it is gradually changed into a very fusibleolive-green substance, the ammonia disappearsentirely, and part of the space which it occu-pied is filled with a quantity of hydrogen ex-actly equal to that which the potassium em-ployed would have given, if thrown into water.This experiment may be performed in a benttube over mercury, but care must be taken toshake off every particle of mercury from thepotassium before it is deposited in the bend ofthe tube. Heat is then applied by a spiritlamp, and soon the potassium melts and be-comes covered with a thin crust which directlyafter disappears, leaving the surface very bril-liant, in a few seconds much ammonia is ab-sorbed, and the olive-green substance is pro-duced. By using sufficient ammonia all thepotassium is changed to this olive-green matter.The quantity of ammonia absorbed varies fromless than 100 to l.'JO times the bulk of the po-tassium, according to the heat employed.This olive-green substance is opake, and heavierthan water, when heated it melts and disen-gages ammonia, hydrogen, and azote, and thensolidifies, still retaining its green colour. Whenexposed to the air at a common temperature,it gradually changes to ammonia and potash.When thrown into a heated crucible it suddenly8 Recherche? Physico-Chimiquc?, fait
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inflames. It burns rapidly when heated inoxygen gas. In water it heats and is immedi-ately decomposed into potash and ammenia.The same effect takes place with acids. Whenheated with most of the metals, particularly theeasily fusible ones, azote, ammonia, and some-times hydrogen are disengaged, and an alloyof potassium with the metal used is obtained.M. M. Gay Lu-sac and Tlienard examinedwith much care the effects produced by theapplication of different degrees of heat to inisolive-green matter. The potassium was firstput'into a glass vessel with a certain quantityof pure hydrogen, to preserve the potassiumfrom the contact of the mercury by which itwas confined. Some pure ammoniacal gas wasthen added, and the whole was heated till theolive-green matter was produced, and whencold the absorption of ammonia was ascertained.The olive-green matter was then heated gradu-ally to redness in the same vessel, without beingremoved, when it melted, boiled, and finallybecame solid again, blackish, and was no longerfusible. The remaining ammonia was thenabsorbed by water, and the azote and hydrogenanalyzed in Volta’s eudiometer. The generalresults of several experiments at different de-grees of heat was, that as soon as the heat issufficient to melt the olive-green matter, itbegins to give out gas •, that as long as theheat does not quite reach a cherry red, thegas is only ammonia ; but by raising the beatto low redness, much hydrogen and azote be-come mixed with the ammonia given out; andat a higher heat, the gas becomes entirely hy-drogen^ and azote, in the proportions of threeto one, that is, in which they constitute ammo-nia ; but however long the heat is continued,no more than about three-fifths of the quantityof gas originally absorbed by the potassiumis expelled, so that it does not return to thestate of potassium, but to a blackish infusiblecompound.
When this olive-green matter is confinedover mercury and a drop of water is let upto it, much heat is excited, and a good dead ofgas generated. By carefully adding water aslong as any gas is generated, and assising theprocess by a gentle heat, the whole is convertedinto a lump of moist solid potash and pureammoniacal gas ; and it was found that theammonia obtained was’ almost equal to thatwhich had boon originally absorbed by thepotassium, during its conversion into the ofive-grecn matter, the slight difference in quantity'