148 On the Formation of Ammonia, $c. [1825* 



mingled with the metal, than ammonia was developed, which 

 rendered the turmeric paper brown, the original yellow re-ap- 

 pearing by the application of heat to the part. 



Still anxious to obtain a potash which should be unexcep- 

 tionably free from any source of nitrogen, I heated a portion of 

 potash with zinc, endeavouring to exhaust anything it might 

 contain which could give rise to the formation of ammonia : it 

 was then dissolved in pure water, allowed to settle, the clear 

 portion poured off and evaporated in a flask by boiling ; but 

 the potash thus prepared gave ammonia, when heated with 

 zinc, in hydrogen gas. 



With regard to the evidence of the nature of the substance 

 produced, it was concluded to be ammonia in the experiments 

 made in hydrogen, from its changing the colour of turmeric 

 paper to reddish- brown ; from the disappearance of the red- 

 dish-brown tint and' reproduction of yellow colour by heat ; 

 from its solubility in water, as evinced by the greater depth of 

 colour on moist turmeric paper than on dry ; from its odour ; 

 and from its yielding white fumes with the vapour of muriatic 

 acid. When formed in open tubes, its nature was still further 

 tested by its neutralizing acids and restoring the blue colour 

 of reddened litmus paper ; by its rendering a minute drop of 

 sulphate of copper on a slip of white paper deep blue ; and 

 also, at the suggestion of Dr. Paris, by introducing into it a 

 slip of paper moistened in a mixed solution of nitrate of silver 

 and arsenious acid, the yellow tint of arsenite of silver being 

 immediately produced. 



These experiments upon the production of ammonia from 

 substances apparently containing no nitrogen, will call to mind 

 that made by Mr. Woodhouse, of Philadelphia, on the action 

 of water on a calcined mixture of charcoal and potash, during 

 which much ammonia was produced * ; and also the strict 

 investigation of that experiment made by the President of the 

 Royal Society during his inquiries into the nature of elementary 

 bodies f. Sir Humphry Davy found that when one part of 

 potash and four of charcoal were ignited in close vessels 

 cooled out of contact of the atmosphere, pure water admitted 

 to the mixture, and the whole distilled, small quantities of am- 

 monia were produced. That when the operation was repeated 



Nicholson's Journal, xxi. 290. t Phil, Trans. 1809, p. 100; 1810, p. 43. 



