the sevefiiiWti%^ in the Atmosphere, 249 



•as it apf)ears'irom my' expenehce tb be not 

 only the most elegant and expeditious of all 

 the methods hitherto used, but also as correct 

 Jis any' of'rticm, wKeii properly conducted,* 1 

 shall, on this occasion, "animadivert iipon it. 



1. Nitrous gas may be obtained pure by 

 nitric acid diluted with an equal bulk of water 

 poured upon copper or mercury; little orno 

 artificial heat should be applied. — The last 

 product of gas this" -W^iy obtained, does not 

 contain any sensible portion of azotic gas ; at 

 feast It JP^y easily be got with less than 2 or 

 3 pdr cent, of that gas: It is probably nearly 

 free from nitrous oxide also, when thus ob- 

 tained. 



'^.^Tf^l'OO measures of comnion air be put 

 to "36 qf pure nitrous gas in a tube 3- 10th of 

 an inch wide and 5 inches long, after a few 

 minutes the whole will be reduced to 79 or 

 80 measures, and exhibit no signs of either 

 oxygenous or nitrous gas. 



' S. If 100 measiires of common air be ad- 

 mitted to 72 of nitrous gas in a wide vessel 

 over water, such as to form a thin stratum of 

 air, and an immediate momentary agitation be 

 used, there will, as before, be found 79 or 80 

 measures of pure azotic gas for a residuum. 



' , in the last experiment, less than 72 

 measures of nitrous gas be used, there will be a 

 I i 



