[ l6 9 ] 
air it contains in the foregoing manner : I therefore 
made ufe of the following method. 
Three fmall phials were weighed together in the 
fame fcale. The firft contained fome weak fpirit of 
fait, the fecond contained fome volatile fal ammoniac 
in moderate fized lumps without powder, corked up 
to prevent evaporation, and the third, intended for 
mixing the acid and alcali in, contained only a little 
water, and was covered with a paper cap, to prevent 
the fmall jets of liquor, which are thrown up during 
the effervefcence, from efcaping out of the bottle. In 
order to prevent too violent an effervefcence, the acid 
and alcali were both added by a little at a time, care 
being taken that the acid (hould always predominate 
in the mixture. Care was alfo taken always to cover 
the bottle with the paper cap, as foon as any of the 
acid or alcali were added. As foon as the mixture 
was finifhed, the three phials were weighed again ; 
whereby the lofs in effervefcence was found to be 134 
grains. The weight of the volatile fait made ufe of was 
2 54 g r ains, and was pretty exactly fufficient to faturate 
the acid. The lolution appeared, by pouring fome 
of it into lime water, to contain fcarce any fixed air. 
Therefore 254 grains of the volatile fal ammoniac 
contain 134 grains of fixed air, i, e. °f their 
weight. It appeared from the fame experiment, that 
1680 grains of the volatile fait faturate as much acid 
as 1000 grains of marble. 
By another experiment, tried with fome of the 
fame parcel of volatile fait, it was found to contain 
AVV of its weight of fixed air, and 1643 grains 65 
it faturated as much acid as 1000 grains of marble. 
By a medium, the fait contained of its weight 
Vol. LVI. Z of 
