[63 



n. The V.akeiian Lecture. An AccouJit of some new anahj- 

 tical Resertrches on the Nature of certain Bodies, particu- 

 Inrhj the Alkalies, Phosphorus, Sulphur, Carbonaceous 

 Matter, and the Acids hitherto undecornposed ; with some 

 general Observations on Chemical Theonj. By Humphry 

 Daw, Esq., Sec. R.S., F.R.S. Edin., and M.R.LA. 



[Continued frcm vol. ixxiii. p. 488.] 



As an inflammable gas alone, having the obvious properties 

 of hydrogen is given off during the action of potassium upon 

 amiponia, and as nothing but gases apparently the same as 

 hydrogen and nitfogen, nearly in the proportions in which 

 they exist in volatile alkali, are evolved during the exposure 

 of the eonipound to the degree of heat which I have speci- 

 fied ; and as the residual substance produces ammonia with 

 a little hydrogen by the action of water, it occurred to me, 

 that, on the principles of the antiphlogistic theory, it ought 

 to be a compound of potassium, a little oxygen and nitro- 

 gen, or a combination of a suboxide of potassium and nitro- 

 gen; for the hydrogen disengaged in the operations of which 

 it was the result, nearly equalled the whole quantify con- 

 tained in the ammonia employed ; and it was easy to explain 

 the fact of the reproduction of the ammonia by water, on 

 the supposition, that by combination with one portion of 

 the oxyojen of the water, the oxide of potassium became pot- 

 ash, and by combination with another portion and its hydro- 

 gen, the nitrogen was converted into volatile alkali. 



With a view to ascertain this point, I made several expe- 

 riments on various residuur-.i!:, procured in the way that I 

 have just stated, from the action of equal quantities of potas- 

 sium on dry ammotiia in platina trays, each portion of meta} 

 equalling six grains. 



In the first trials, 1 endeavoured to ascertain the quantity 

 of ammonia generated by the action of water upon a resi- 

 duum, by heating it with muriate of lime or potash partially 

 deprived of moisture ; and after several trials, many of which 

 failed, I succeeded in obtaining four cubical inches and a half 

 of ainmouia. In three other cast:!, where there was' reason 



to 



