1825.] On the Formation of Ammonia, $c, 151 



though not in an exact way, by heating a little tartrate of lead 

 with potash in a tube in the flame of a spirit-lamp, driving off 

 the water and first products, and raising the residue to dull 

 redness. If a drop of water be allowed to flow down on to the 

 residue when cold, and it be then heated, ammonia will be 

 found to rise with the water. 



I was induced in the course of these experiments to try again 

 and again, whether the potash or lime would not yield ammonia 

 when heated alone ; but when well prepared, and the tubes 

 experimented in perfectly clean, they gave no indications of it. 

 By exposure to air for three days in a room, hydrate of lime 

 appeared to have acquired the power of evolving a little am- 

 monia when heated, and caustic lime so exposed gave still 

 stronger traces of it. Potash also exhibited an effect of this 

 kind, and potash which had been heated with zinc, and con- 

 tained oxide of zinc, most decidedly. Some potash and zinc were 

 heated together ; a part was immediately put into a clean close 

 bottle ; another part was dissolved in pure water, decanted, the 

 solution evaporated in a covered Wedgewood's basin, and then 

 also set aside in a close vessel for twenty-four hours : at the end 

 of that time the first portion, heated in a tube, gave no decided 

 trace of ammonia, but the latter yielded very distinct evidence 

 of its presence, having apparently absorbed the substance which 

 was its source from the atmosphere during the operations it 

 had been submitted to. White Cornish clay being heated red- 

 hot, and then exposed to the air for a week, gave plenty of 

 ammonia when heated in a tube. When the substances were 

 preserved in well-stoppered phials, these effects were not pro- 

 duced. 



Such are the general and some of the particular facts which 

 I have observed relative to this anomalous production of am- 

 monia. I have refrained from all reasoning upon the proba- 

 bility of the compound nature of nitrogen ; or upon what might 

 be imagined to be its elements, not seeing sufficient to justify 

 more than private opinion on that matter. I have endeavoured 

 to make the principal experiments as unexceptionable as pos- 

 sible, by excluding every source of nitrogen, but I must con- 

 fess I have not convinced myself I have succeeded. The results 

 seem to me of such a nature as to deserve attention, and if it 

 should hereafter be proved that nitrogen had entered in some 



