360 



NEW METHOD OF ANALYSING AMMONIA. 



but varying in ever, that the appearance varied as to its degree, I was in, 

 Th^experi- duced *o repeat the process with redoubled precaution ; fig- 

 ment repeated ing the globe, previously heated with hot mercury, and 

 caution!*' Fe " dr >' in o n otonly the quicksilver, but the iron cistern which 

 contained it, by exposure to long continued heat. The elec. 

 Little or no trified gas now betrayed no signs of moisture on the applica- 

 tion of a temperature 20 p of Fahrenheit; and gave only 

 the smallest perceptible traces, by a cold of 0? or a few de, 

 grees below. I cannot help suspecting, therefore, that the 

 moisture, manifested in the earlier experiments, was derived 

 from the mercury or from some extraneous source, and was 

 not generated by the action of electricity #, 

 Avidity of am- The avidity with which ammonia retains moisture, and 

 sture. 3 ° r m01 " a o a ' n absorbs it when artificially dried, is very remarkable, 

 A confined quantity of common air may be completely de- 

 siccated, in the space of a few minutes, by pure potash, or 

 by muriate of lime ; so that no ice shall appear in the inner 

 surface of the containing vessel, when exposed to a cold 

 of — 26? of Fahreuheit. But ammonia requires exposure 

 during some hours to potash, to stand the test even of 

 Q Fahrenheit; and a single transfer of the dried gas, 

 through the mercury of a trough in ordinary use, again 

 communicates moisture to it. Muriatic acid gas, freed 

 merely from visible moisture, deposits no water at the tem- 

 perature of 26? Fahrenheit. This is probably owing to its 

 strong affinity for water; for electricity, after the full 

 action of muriate of lime, evolves, as I have lately ascer- 

 tained, about ~ its bulk of hidrogen gas, the recent, mu, 

 riatic acid gas giving about T Vth after the same treatment +, 



From 

 * It may be objected, I am aware, that as the gasses produced 

 from ammonia are nearly double its original bulk, they may hold 

 in combination any water that may have been generated by elec- 

 tricity. But though this supposition may explain the nonappear-: 

 I ance of visible moisture, it does not account for the inefficiency 



of a powerful cooling cause to discover traces of watery vapour : 

 for this is a test which renders apparent very minute quantities of 

 water in gasses. *■; *,- 



f lu a course of experiments, which I have described in the 

 Philosophical Transactions for 1800, it appeared that muriatic acid, 

 gas, after being dried by muriate of lime, gave nearly as much 



hidrogen, 



