of British and Foreign Salt toy 
and dryness, and that no change of temperature happened 
during the experiment. 
"4C0 grains of the less pure kind of rock 
Hundredths 
of a cub. in. 
Henre its 
specific 
salt, broken down into small fragments, 
gray, was* 
filled the space of - 
75 
2112 
400 grains of stoved salt - 
- 75 
2112 
400 do. (another sample) 
- 76 
2084 
400 do. common salt - 
7 6 
to 
O 
CO 
f 400 large grained fishery salt - 
- 83 
1909 
<; 400 do. (another sample) 
- 83 
1909 
|_4oo St. Ube's - 
82 
1992 
If the above mode of determination at all approach to cor- 
rectness, it would appear that the specific gravity of rock salt 
is diminished, by being broken into small fragments, from 
2125 to 2112, probably in consequence of the quantity of air 
which the fragments envelope, and which cannot be entirely 
separated by agitation. From the numbers given in the last 
column, it is evident, that the smaller grained salts are spe- 
cifically heavier than those which are composed of larger and 
more perfect crystals. A difference of only one or two hun- 
dredth parts of a cubic inch, is perhaps entitled, in a process 
of this kind, to little reliance ; and I do not therefore regard 
it as indicating any material difference in the specific gravity 
of the first four, or last three salts submitted to experiment. 
But when the difference amounts to eight hundredths, as be- 
tween the small and large grained salt, it may safely be 
imputed to an inferior specific gravity in that species, which 
occupies so much greater a proportional bulk.'* 
* Distilled water at 1000 being taken as the standard, 
f M. Hassenfratz seems to have suspected that a difference in the specific 
P 2 
