f 40 | 
Let us. fuppofe a meafure to confift of 100 cubic inches, then 
2 meafures of alkaline air will weigh 36,32 grs.; thefe take up 
46,5 of fixed air, and the concrete falt thus formed will weigh 
82,82 grs.; then if 82,82 parts of concrete volatile alkali con- 
tain 36,32 of pure alkali as free from. water as it can be had, 
Ioo parts of this. concrete falt fhould contain 44 nearly of fuch 
alkali, and 56 of fixed air. And here the quantities of thefe 
two ingredients muft always be proportional, as the alkali can- 
not be reduced to a concrete form without a due proportion of 
the aerial, acid, nor, the acid, without the due quantity of alkali. 
Therefore knowing the quantity. of fixed air in any given weight 
of. this, dry falt, we may determine the quantity of alkali by the 
above analogy, and this being found, the qnantity of water ex- 
ceeding that exifting in alkaline and fixed airs muft alfo be 
known, it being the remainder of the given weight of the 
falt. 
Of. Vitriolic Ammoniac. 
100 grs. of mild concrete volatile alkali, formed by fublimation, 
and diffolved in tooo of water, were faturated by 132 of vitriolic 
acid, whofe fpecific gravity was 1,5654, which contained 61 
per cent, ftandard. The lofs of air was 45 grs. and hence the 
quantity of mere alkali was 35,35 ers. the fpecific gravity of 
the folution in temperature 59° was 1,0627. 
Tue fpecific gravity of a folution of 100 grs. of cryftallized 
vitriolic ammoniac in 821 gts. of water and temperature 59° was 
alfo 
