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prefervation of the more delicate' birds, fifhes, fruity, 
&c. 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 ft ate ; 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 fenfible effect ; which rather furprized 
me ; as, from the refult of the experiment with the 
iron filings and brimftone, I had expefted 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 effeft upon 
common air, both of them diminifhing 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 
difl'olved in fpirit of nitre, to which as much water, 
was added, yielded about twelve ounce meafures of 
air, which had, in fome degree, the properties of 
nitrous air, making a flight effervefcence with com- 
mon air, and diminiftiing it about as much as ni- 
*■ ’ trous 
