on various Ohject$, 403 



can procure from a given quantity of ammonia, rhore than 

 its volume of hydrogen. 



Whence, they ask, can the hydrogen proceed ? — Shall 

 it be admitted that it is from the ammonia? But this, say 

 they, is impossible; for all the ammonia is reproduced. It 

 must then conie from the water which may be supposed 

 to be in the ammonia, or from the metal itself. But the 

 experiments of M. BerthoUet, jun. prove that ammonia - 

 does not contain any sensible quantity of water. There- 

 fore, say they, the hydrogen gas must be produced from 

 the metal; and as, when this gas is separated, the metal is 

 transformed into potash, the metal appears to be nothing 

 more than a combination of hydrogen, and that alkali. 



It is obvious, that even supposing the statement of these 

 gentlemen correct, their conclusions may easily be contro- 

 verted. They affirm that all the ammonia is reproduced; 

 but they do not obtain it without the addition of water. 

 And of the oxygen which this would give to the potas- 

 sium, and of the hydrogen which it might furnish, to re- 

 produce the ammonia, they take no notice. 



I have shown, by numerous experiments, many of which 

 have been repeated before members of this society, that 

 the results obtained, by applying heat to the fusible sub- 

 stance, are very different from those stated by the ingenious 

 French chemists, when the operations are conducted in a 

 refined and accurate manner. 



In proportion as more precautions are taken to prevent 

 moisture from being communicated to it, so in proportion 

 is less ammonia regenerated ; and I have seldom obtained 

 as much as yV ^^ ^^^ quantity absorbed. And Ihave never 

 procured hydrogen and nitrogen, in the proportions in 

 which they exist in ammonia ; but there has been always 

 an excess of nitrogen. 



The processes which I have detailed in the last Bakerjan 

 lecture, and in the appendix to it, show this ; and they 

 likewise show that a considerable quantity of potassium is 

 always revived. 



I have lately performed the experiments^ in a manner 

 which I proposed, page 458 of the last volume of the 

 Transactions [Phil. Mag. vol. xxxiv. p. 344.] and ^the re- 

 sults have been very satisfactory; as far as they relate to 

 the question of the nature of potassium. 



I employed a tube of platina bored from a single piece, 



"Which having a stop-cock and adaptor of brass, connected 



with the mercurial apparatus, could be used as a retort; the 



C c 2 potassium 



