<md the f em ;„ g Converfton of Water into Air. 
tube of the fame compofition with the retort, and putting a 
“ ra - - *. cJoZZ “'if; ? l,fs 
”,Ued",l •” '!r b “' ■'”'*!> -II .hifubn.,™" 
enabled he earthen tube to give air, in the fame proportio, 
‘ 1 ° 1 16 ^ lme quality, as it would have done if it h-fl I 
expofed to the naked fire. had beC, ‘ 
Having now procured air, by means of a water in n „ 
tap* ,„d, „ , ,b.„ sht , ul ,, raftionabk 
make it in greater quantities in proportion to the water cm 
LToftheth 1 - t r t . hi % P ) Urp ° re Ifirit bought of increafing the 
te thicknefs of the porous retorts; but I thought it might 
of “ ,f 1 PUt r° the ret ° rt ’ !n P° wder > the materials 
Winch they were made, or other fubrtances of the fame kind 
Accordingly, by mixing ground flint and clay in various- 
! roportions, Iprefently increafed the quantity of air much be- 
r m j “pfr- ■” *. « ■»!.. i.. wiic, i 
2 ; . ; ; °> ”“ r - T| *», ,„d lcf , 
flint, I had ft, 11 more air; and at laft, leaving out the flint 
altogether, and ufing clay only, I never failed to get much 
more than 400, and generally between 5 oo and 6o°o, ounce 
mcafures of air from one of water, which was about three- 
fourths of the weight of the water; and in one particular pro- 
cefs I procured very little left than nine-tenths of the weight 
0 lew ate, in a,r, and tins air was never much lefs pure than 
at of the .atmofphere. Sometimes it could not be diftinguilhed 
at all from it at all by the teft of nitrous air ; and once or twice 
1 thought it even purer than that of the atmofphere. 
1 muft here obferve, that I found it not convenient to put fo 
much water to any quantity of clay as would make it cohere 
m one mais but only fo much as that it Ihould remain in the 
Vol. LXXIII. K k k fmm 
