Mr. Cavennisu's Exseriments -on Air. 1,63, 
poftion’ of fixed air, and then let fall a few drops of it into lime:, 
water} -not the fmalleft cloud was -perceived, and yet.when. L, 
breathed into it afterwards, it-became milky ina few feconds ;: 
fo: that: ‘this-experiment 1 is, perfedtly: aialogonate to that in which. 
nitrous-and common air were mixed. ni gece ad 
» But if nitrous air and common air be mixed over (6 ie Mere, 
cury, the refult is intirely adverfe to the opinion of MroCa-. 
VENDIsH; and favourable to mine; for. in this cafe the com-. 
mon air is not at all diminifhed until water is admitted to it, and) 
the mixture agitated a few minutes,- and then the dimiaution. 1 1s. 
nearly ‘the fame as if the mixture were made over, water... Thus 
when I mixed two cubic inches, of common air with one.of, 
nitrous air, they. occupied the. {pace of two inches and .one- 
eighth; and the -furface of the mercury was immediately .cal- . 
cinéed ; which fhews that the inch of nitrous air was decom-. 
pofed, and produced‘ nitrous acid ; but the common ait. was. un-. 
diminifhed ; and the,one eighth of an inch over and above. the. 
two inches,of common air, proceeded from an. addition of, new, 
nitrous air, formed by. the corrofion of the furface of the mer-.. 
cury... That the common air, fhould remain, undiminithed. is., 
eafily explained in my fyftem, becaufe fixed, alr AS), formed,, 
which, on this occafion, muft remain eutitecbed. at leaft for 
a long time, as there is nothing; at hand that can immediately 
receive it 3 and hence, if water be admitted foon after the mix- 
turé of both airs} the diminution will be nearly: the fame as?if 
the siixture’ had! been originally! made over water, ‘though ict“ 
exactly the fame ;“becaufe the: nitrous air, produced by the? 
union of the newly formed: nitrous-acid with’ the mercury,: is¢ 
not entirely -abforbable by water-But, in.Mr. Cavenpdisn’s® 
hypothefis, the'common air fhoald be diminifhed juft as-much: 
asif the mixture were: made over water ; for, accdrding to. him, {. 
ons Nie this 
