to my firft refolutton, under an abfolnte neceftity pF 

 giving a name to this kind of air myfelf. When I 

 firft began to fpeak and write of it to my friends, I 

 happened to diftinguifh it by the name of nitrous air, 

 becaufe I had procured it by means of fpirit of nitre 

 only; and though I cannot fay that I altogether like 

 the term, becaufe this air is not got from all the me- 

 tals by the fame fpirit, neither myfelf nor any 

 of my friends, to whom I have applied for the pur- 

 pofe, have been able to hit upon a better ; fo that 

 I am obliged, after all, to content myfelf with it. 



I have found that this kind of air is readily pro- 

 cured from iron, copper, brafs, tin, lilver, quickfil- 

 ver, bifmuth, and nickel, by the nitrous acid only, 

 and from gold and the regulus of antimony by aqua 

 regia. The circumftances attending the folution of 

 each of thefe metals are various, but hardly worth 

 mentioning, in treating of the properties of the air 

 which they yield, which, from what metal foever "rt 

 is extracted, has, as far as I have been able to ob- 

 ferve, the very fame properties. 



One of the moil confpicuous properties of this kind 

 of air is the great diminution of any quantity of com- 

 mon air with which it is mixed, attended with a tur- 

 bid red, or deep orange colour, and a considerable 

 heat. The fmell of it, alfo, is very ftrong, and re- 

 markable, but very, much refembling that of imoking 

 fpirit of nitre. 



The diminution of a mixture of this and common 

 air is not an equal diminution of both the kinds, 

 which is all that Dr. Hales could obferve, but of the 

 common air chiefly, though not wholly. For if one 

 meafure of nitrous air be put to two mcafures of 

 E e 2 common 



