20 PHILOSOPHICAL TRANSACTIONS. [ANNO J 781. 



gr. and 100 gr. should lose 44.08 ; but of these 44.08, 32.42 were fixed air, as 



is already seen, therefore the remainder, that is, 1 1 .66 gr. were water, and the 



quantity of pure calcareous earth in lOOgr, of the marble was 55.Q2 gr. 



I next proceeded to discover the specific gravity of the lime. Into a brass 



box, which weighed 607-65 gr. and in the bottom of which a small hole was 



drilled, I stuffed as much as possible of the _ . 



drains. 

 finely powdered lime, and then screwed the Weight of the box in air . . o'o7.6'5 



cover on, and weighed it both in air and water. Ill l "Z° f f w ,u Sl u m *??• " 73 ' 75 



, T . . Weight of the box and lime 



When immersed in this latter, a considerable in air 1013.3 



quantity of common air was expelled; when Weight of lime singly in air. 135.85 



. . , .... „. . ,. Loss ot weight of the box and 



this ceased, 1 weighed it. Ihe result of tins lime in water 256.5 



experiment was as annexed : Loss of wei S ht of lime s ™E l y ' S2.3 



Hence, dividing the absolute weight of the lime by its loss in water, its specific 

 gravity was found to be 2.3Q08. 



From these data I deduced the specific gravity of fixed air in its fixed state ; 

 for 100 gr. of marble consist of 55. 02 of earth, 32.42 of fixed air, and 1 1.66 

 of water; and the specific gravity of the marble is 2.717- Now the specific 

 gravity of the fixed air, in its fixed state, is as its absolute weight divided by its 

 loss of weight in water ; and its loss of weight in water is as the loss of 100 gr. 

 of marble minus the losses of the pure calcareous earth and of the water. 



Loss of 100 gr. of marble = = is6.8 gr. 



6 2.7 17 



55 9'2 

 Loss of 55.92 gr. calcareous earth = • — — = 23.39 gr. 



2.390 6 



Loss of 1 1 .66 gr. water = 1 1 .66 



Sum 35.05 



Then the loss of the fixed air 36.8 — 35.05 = 1.75 ; consequently, its spe- 

 cific gravity is — '■=-? = 18.52 ; by which it appears to be the heaviest of all acids, 

 or even of all bodies yet known, gold and platina excepted. 



Of fixed vegetable alkali. — As the manner of conducting the experiments 

 made on this salt was nearly the same as that used in the foregoing, except that 

 to find its specific gravity I weighed it in aether instead of water, I shall content 

 myself, to avoid the repetition of tedious calculation, with relating the result of 

 these experiments. 1st. I found that lOOgr. of this alkali contain about 6.7 gr. 

 of earth, which, according to Mr. Bergman, is siliceous : this earth passes the 

 filter with it when the alkali is not saturated with fixed air, so that it seems to 

 be held in solution as in liquor silicum. 2uMy. I found, that the quantity of 

 fixed air in oil of tartar and dry vegetable fixed alkali, is various at various times 

 and in various parcels of the same salt ; but that at a medium in the purer alkalis 

 it maybe rated at 21 gr. in 100 ; and hence the quantity of this alkali in any 

 solution of it may be very nearly guessed at, by adding a known weight of a 



