formation of Ammoniay &c. 25 



water and first products, and raising tlie 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 Avould not yield ammonia 

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

 rimented 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 ammonia 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 contained oxide of zinc, mostd ecidedly. 

 Some potash and zinc were heated together ; a part was imme- 

 diately 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 

 24 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 

 produced. 



Such are the general and some of the particular facts which I 

 have observed relative to this anomalous production of ammonia. 

 I have refrained from all reasoning upon the probability 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 prin- 

 cipal experiments as unexceptionable as possible, by excluding 

 every source of nitrogen, but I must confess 1 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 



