ble matter, 0°044 of muriate of lime, 0°506 of 
muriate of magnesia, 0°7 of sulphate of lime, 
0°398 of sulphate of magnesia, and 98:287 of 
chloride of sodium; a specimen of Dutch salt, in 
smaller grain than the preceding, but still re- 
markable for the regularity of its crystals, con- 
tained 0:09 per cent. of insoluble matter, 0:099 of 
muriate of lime, 0°201 of muriate of magnesia, 
0:4 of sulphate of lime, 0°2985 of sulphate of 
magnesia, and 98:9115 of chloride of sodium; 
and a specimen of Dutch salt, in less regular and 
much smaller crystals than the preceding, but 
still more symmetrical in crystal than British 
salt of the same size of grain, contained 0°07 per 
cent. of insoluble matter, 0°0935 of muriate of 
lime, 0°1765 of muriate of magnesia, 0°57 of sul- 
phate of lime, 0°4415 of sulphate of magnesia, 
and 98'6485 of chloride of sodium. The analysis 
| of specimens of four different kinds of Cheshire 
| rock-salt may be advantageously compared with 
these analyses of sea-salts, for the purpose of 
| guiding purchasers who use large quantities of 
| salt as a condiment for cattle, and especially as 
_ an antiseptic. A specimen of crushed rock-salt, 
| analysed by Dr. Henry, contained 0:1 per cent. 
| of insoluble matter, 0:0063 of muriate of lime, 
| 0:0187 of muriate of magnesia, 0:65 of sulphate 
of lime, and 98°325 of chloride of sodium; a 
specimen of fishery rock-salt. contained 0:1 per 
cent. of insoluble matter, 0:025 of muriate of 
lime, 0°075 of muriate of magnesia, 1-125 of sul- 
phate of lime, and 98°675 of chloride of sodium ; 
a specimen of common rock-salt contained 0:1 
per cent. of insoluble matter, 0:025 of muriate of 
lime, 0:075 of muriate of magnesia, 1:45 of sul- 
phate of lime, and 98°35 of chloride of sodium ; 
| and a specimen of store rock salt contained 0°1 
per cent. of insoluble matter, 0°025 of muriate of 
lime, 0:075 of muriate of magnesia, 1:55 of sul- 
phate of lime, and 98:25 of chloride of sodium. 
“On comparing these analyses,” remarks Pro- 
fessor Traill, “we find that the Dutch salt is 
very. superior in purity to bay salt, and still more 
so to most of the salt obtained in Britain from 
sea-water. The specimens even surpassin purity 
the salt prepared from Cheshire rock-salt. This 
is chiefly owing to their containing less sulphate 
| of lime than the salt of Cheshire; while, how- 
|| ever, they are contaminated with larger propor- 
tions of the earthy muriates and sulphate of 
magnesia, from all which the Cheshire salt is re- 
markably free. The contaminating saline in- 
gredients which are most detrimental to salt, as 
a preservative for meat, are undoubtedly the 
| earthy muriates or hydrochlorates, and next to | 
these, the sulphate of magnesia, because they are 
either very soluble or deliquescent, and therefore 
cause rapid melting of the common salt, into 
which they largely enter, and thus its value in 
the preservation of fish and flesh is greatly im- 
paired. When a salt of easy solubility is applied 
to preserve fish or flesh, it soon dissolves in the 
animal juices, and readily absorbs moisture from 
the air; in that case, the upper portions of the 
fish or flesh are speedily deprived of the salt, and 
thus become liable to pass to putrefaction. The 
remarkable purity of the Cheshire salt from de- 
liquescent saline contaminations, would seem to 
point out its peculiar fitness for the fisheries, 
and the salting of animal flesh; yet I believe it 
is admitted, that Dutch salt is preferable for the 
first, which must depend on some of its other 
qualities. On examination, it would seem that 
its value for such purposes depends on its supe- 
rior hardness, and the size of its grain. The 
large-grained and dense salt, when strewed be- 
tween the layers of fish or flesh in a cask, every 
other thing being equal, will remain longest 
solid, and by its very gradual dissolving, con- 
tinue to afford a succession of saline particles to 
the upper portions of the animal matter, as well 
as to the lower, and to keep it thoroughly im- 
pregnated with salt. A large-grained hard salt 
has been formed by a slow evaporation; and if 
the very pure salt of Cheshire were crystallized 
more slowly than it is, there can be no doubt 
that it would afford a fishery salt superior to 
every other now in use. For the first part of 
the process of salting meat, the formation of the 
brine for immersion of the animal matter, and 
what is called striking it with salt, the small- 
grained pure salts are perfectly applicable ; and 
for this purpose, I do not think that the third 
kind, or even the second kind, of the Dutch salt, 
mentioned in the analysis, has any superiority 
over the Cheshire salt ; but the large and hard 
grain of the first kind of the Dutch salt more than | 
compensates for any little inferior degree of purity, - 
when employed for strewing between layers of fish 
or flesh in the casks. For the due preservation of 
butter, no kind of salt seems preferable to the | 
larger grained varieties of Cheshire salt. The 
sulphate of lime, as it exists in this salt, is of | 
small consequence ; while its extreme purity 
from the contamination of earthy hydrochlorates 
and of the bitter sulphate of magnesia, render it 
but little likely to impart any disagreeable fla- 
vour to that delicate article of diet.” 
Rock salt occurs in the sides and bottoms of 
salt lakes in America, and in vast beds of the sali- 
ferous sandstone formation in England, in Con- 
tinental Europe, and in most other parts of the 
world. The beds of it in Cheshire vary in thick- 
ness from 4 to 130 feet; and alternate with lime- 
stone, clay, swinestone, sandstone, and indurat- 
ed, gypseous marls. It occurs both massive and 
dentiform, and also in straight and curved fibrous 
concretions, and is commonly yellowish, greyish, 
or very white, with flesh-coloured, red, and vio- 
let. stripes, and-is highly translucent or almost 
semitransparent, and breaks into splintery frag- 
ments, and presents externally a resinous lustre, 
and internally a shining and glistening appear- 
ance; and, when exposed to strong heat either 
on the coals or from the blow-pipe, it smartly 
decrepitates. A peculiar kind of it decrepitates 
nga 
