Manchester Memoirs, Vol. xliv. (1900), No. V\. i 



XIII. On the Production of Nitric Acid from Air by 

 means of the Electric Flame. 



By Arthur McDougall, B.Sc, 



AND 



Fred Howles, B.Sc. 



Received ami read March 6th, igoo. 



Nitric acid has been known and used from very early 

 times. We find the Arabian alchemist, Geber, teaching 

 the method of obtaining it by distilling a mixture of 

 saltpetre, copper vitriol, and alum in certain proportions. 

 Raymund Lullius, in the 13th century, gave directions for 

 preparing it by distilling saltpetre with iron vitriol. 

 Glauber, in the 17th century, obtained it by distilling 

 saltpetre with oil of vitriol, the process by which it is 

 prepared at the present day. 



It is not, however, until we come to the beginning of 

 the 19th century, that any mention is made of preparing 

 nitric acid by other means than that of distilling saltpetre 

 with oil of vitriol. 



It was Cavendish who, at this time, succeeded in 

 demonstrating that atmospheric air is a mixture of 

 oxygen (dephlogisticated air) and nitrogen (phlogisticated 

 air) in constant proportions, and that nitric acid can be 

 produced by the passage of electric sparks through these 

 gases confined over water. 



By the substitution of potash solution for water a 

 mixture of nitrite and nitrate of potash is produced, which, 

 on evaporation, yields saltpetre ; and, as we already know, 

 nitric acid can be obtained from this salt by distillation 

 with oil of vitriol. In this way Cavendish succeeded in 

 preparing, under favourable conditions, saltpetre, at the 

 rate of 0'0036o7 grm. per hour. 



August i6t/i, I goo. 



