108 Dr. Henry's Analysis of several Varieties 
The last series of experiments proves decisively, that in an 
important quality, (viz. that of specific gravity,) which is 
probably connected with the mechanical property of hardness 
and compactness of crystals, little or no difference is dis- 
coverable between the large grained salt of British, and that 
of foreign manufacture. If no superiority, then, be claimed 
for British salt as applicable to economical purposes, on ac- 
count of the greater degree of chemical purity which unques- 
tionably belongs to it, it may safely, I believe, be asserted that 
the larger grained varieties are, as to their mechanical pro- 
perties, fully equal to the foreign bay salt. And the period, 
it may be hoped, is not far distant, when a prejudice ( for such, 
from the result of this investigation, it appears to be,) will be 
done away, which has long proved injurious to the interests 
and prosperity of an important branch of British manufacture. 
Section III. Account of the Methods of Analyzing the 
several Varieties of Muriate of Soda. 
The method of analysis which I adopted, in examining the 
several varieties of muriate of soda, was as follows. 
When the salt was in a state of solution, a measured quantity 
was evaporated to dryness in a sand heat, which was carefully 
regulated, to avoid the decomposition of the muriate of mag- 
nesia, if any of that salt were present in the solution.* 
gravity of the same salt may be occasioned by a variation in its state of crystallization. 
De la Pesanteur specifique des Sels, Ann. de Chem. XXVIII. p. 17. 
* Muriate of magnesia, according to Dr. Marcet, begins to part with its acid at 
a temperature a few degrees above that of boiling water. This fact explains the ob- 
servation of Mr. Kirwan, that too great a heat, employed in the desiccation of 
muriate of magnesia, decreases considerably its solubility in alcohol. (Kirwan on 
Mineral Waters, p. 275.) 
