[ 332 ] 
that diverfity of quantity may fugged a doubt con- 
cerning the validity of his principle. The finking 
of the water in the neck of the matrafs feems to be 
a general pha?nomenon attending the folution of all 
falts j the quantity of the defcent is various from 
to 4. of the whole elevation in thofe falts which I 
have tried. In forming the table, I repeated many 
of the experiments, but found no variation which 
could affedt the general conclufion ; with particular 
attention I repeated the folution of vitriolated tartar, 
for I thought it a very remarkable citcumftance that 
one of the hardeft falts fhould be more diminifhed 
in proportion to its whole bulk than any other, but 
the numbers in the table 22 and ir accurately ex- 
J 
prefied the height before and after folution upon the 
repetition of the experiment, fo that it may be relied 
upon as a certain fadt that a cubic inch of vitriolated 
tartar is by folution in water reduced to half a cubic 
inch, though the water cannot, as appeared from an 
experiment I made, abforb - r o * 0 0 th part, nor, as I 
believe, any part, of that fait without being augment- 
ed in magnitude. It is evident from the table that 
fal gemma?, blue vitriol, corrofive fublimate, calcined 
vitriol, and in general thofe falts which retain the leaft 
water in their compofition and conftitute the hardefi: 
mafies, fink more in proportion to their refpedtive 
bulks than any other. I own myfelf at a lols for a 
general principle to explain this general phaenomenon, 
unlefs the air contained in the feveral falts may be 
efteemed fufficient for the purpofe ; a very copious 
feparation of air from the falts during the whole 
time of their folution may be readily obferved in all 
of them, and a fmail portion of it, combined with 
