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prefervation of the more delicate birds, fifties, fruits, 

 Sec. mixing it in different proportions with com* 

 mon or fixed air. Of this property of nitrous air 

 anatomifts may perhaps avail themfelves, as animal 

 fubftances may by this means be preferved in their 

 natural foft ftate ; but how long it will anfwer for 

 this purpofe, experience only can (hew. 



I calcined lead and tin in the manner hereafter 

 defcribed in a quantity of nitrous air^ but with 

 very little feiifible effect ; which rather furprized 

 me ; as, from the refult of the experiment. with the, 

 iron filings and brimftone, I had expected a very 

 great diminution of the nitrous air by this procefs, 

 the mixture of iron filings and brimftone, and the 

 calcination of metals, having the fame effect upon 

 common air, both of them diminishing it in nearly 

 the fame proportion. 



Nitrous air is procured from all the proper me* 

 tals by fpirit of nitre, except lead, and from all 

 the femi-metals that I have tried, except zinc. For 

 this purpofe I have ufed bifmuth and nickel, with 

 fpirit of nitre only, and regulus of antimony and 

 platina, with aqua regia. 



I got little or no air from lead by fpirit of nitre, 

 and have not yet made any experiments to afcer- 

 tain the nature of this folution. With zinc I have 

 taken a little pains. 



Four penny weights and feventeen grains of zinc 

 diffolved in fpirit of nitre, to which as much water 

 was added, yielded about twelve ounce meafures of 

 air, which had, in fbme degree, the properties of 

 nitrous air, making a flight effervefcence with com-; 

 anon air, and diminifhing it about as much as ni- 

 trous^ 



