_Muriate of Soda._ _Common Salt._
QUALITIES. _Form_, that of regular cubes, which do not deliquesce unless
contaminated with muriate of magnesia.[639] CHEMICAL COMPOSITION. It
consists, according to Berzelius, of 46·55 of muriatic acid, and 53·45
of soda; according to the new theory, however, this salt must be
considered as a true _muriate of soda_, only while it remains in aqueous
solution; for when it is reduced to dryness, the muriatic acid and the
soda become both decomposed, and the hydrogen of the former uniting with
the oxygen of the latter, they pass off in the form of water, while the
chlorine of the muriatic acid unites with the metallic base of the soda,
to form _chloride of sodium_, which consists of an atom of each
constituent. It is perhaps difficult to believe that the same salt
should be chloride of sodium in the hand, and muriate of soda in the
mouth! but it is not the less true, nor is it more incredible than the
change which Sulphuret of potass undergoes by solution, the
decomposition of which is rendered evident to the senses by the evolved
sulphuretted hydrogen. Late researches have also detected both in _rock_
and in other salt, the presence of _muriate of potass_, and _muriate of
magnesia_.[640] SOLUBILITY. It is equally soluble in cold and in hot
water, one part of the salt requiring rather more than 2½ parts. MED.
USES. The effects of salt upon the animal and vegetable kingdoms, are
striking and important,[641] and have furnished objects of the most
interesting enquiry to the physiologist, the chemist, the physician, and
the agriculturist; it appears to be a natural stimulant to the digestive
organs; and that animals are instinctively led to immense distances in
pursuit of it; for proof of this fact the reader is referred to “_Parkes
on the repeal of the Salt Laws_,” and to an interesting work by my late
lamented friend, Sir Thomas Bernard, entitled, “_Case of the Salt
Duties, with Proofs and Illustrations_.”[642] Salt, when taken in
moderate quantities, promotes,[643] while in excessive ones, it prevents
digestion; it is therefore tonic and anthelmintic, correcting that
disordered state of the bowels which favours the propagation of worms.
In Ireland, where, from the bad quality of the food, the lower classes
are greatly infested with worms,[644] a draught of salt and water is a
popular and efficacious anthelmintic. _Form: 162_, is a prescription by
Rush, who says that in this manner he has administered many pounds of
common salt with great success in worm cases. In the first volume of the
Medical Transactions we shall find an interesting account of a cure of
this disease by salt, after the failure of other remedies; I beg also to
refer the practitioner to another case illustrative of its anthelmintic
powers, published by Mr. Marshall, (_London Medical and Physical
Journal_, vol. xxxix. No. 231,) which is that of a lady who had a
natural antipathy to salt, and was in consequence most dreadfully
infested with worms during the whole of her life. In very large doses
_Salt_ proves purgative; it is also absorbed, and carried to the
kidneys, but it undergoes no decomposition _in transitu_, nor does it
appear to possess any considerable powers as a diuretic; its solution in
tepid water, in the proportion of ℥ss-℥j in oj of water, forms the
common domestic enema. DOSE, when intended to act as a cathartic,
from℥ss to ℥j very largely diluted; when to answer the other intentions,
from grs. x. to ʒj.