ORIGIN.--Calomel is obtained by heating a mixture of mercurous sulphate
and sodium chlorid. Calomel is found native in Spain and Carniola, but
in too small quantities for commercial value.
PROPERTIES.--Calomel is a dull-white heavy powder. It is inodorous,
insoluble in water, alcohol or ether.
ACTIONS.--Calomel is a cathartic, laxative, alterative, diuretic and
vermifuge. Small doses are laxatives when repeated, large doses are
cathartics, full doses irritate the stomach and produce emesis in man
and dog. By stimulating the urea functions of the liver diuresis are
produced, its action on the liver does not directly increase the
secretion of bile, but removes it from the duodenum which reflexly
increases its secretion. Repeated doses produce mercurial poisoning. It
is an alterative when combined with opium, laxative in small repeated
doses and cathartic in larger doses.
USES.--Calomel is useful in gastric and intestinal catarrh, bilious
diarrhoea, influenza lymphangitis and liver disorders which show
themselves by a yellowness of the visible mucous membranes. It is a
useful adjuvant cathartic conjoined with aloes or other cathartics. As
a laxative or cathartic for horses give aloes and calomel; cattle and
sheep, magnesium and sodium sulphate; for pigs, dogs and cats with
jalap. Pure calomel is a specific for thrush. It is also useful in the
treatment of moist skin and raw sores, mixed in equal parts with bismuth
subnitrate it quickly dries the flesh and prevents itching.
DOSES.--As a laxative vermifuge and alterative horses and cattle take 20
to 40 grs.; sheep and pigs, 5 to 20 grs.; dogs and cats, ¹⁄₁₆ to 1 gr.,
given two or three times a day with equal weight of opium which prevents
griping and a too rapid removal by the bowels. As a cathartic, calomel
is best conjoined with other medicines regulated by that of the medicine
with which it is conjoined. A full cathartic for horses should consist
of calomel 1 to 1¹⁄₂ drs. with aloes 4 to 6 drs.; cattle, 1¹⁄₂ to 2 drs.
with magnesium sulphate or sodium sulphate 1 to 1¹⁄₂ pounds; sheep, 5 to
30 grs. with magnesium sulphate 4 to 8 ounces; pigs, 5 to 30 grs. with
sodium bicarbonate ¹⁄₂ to 1 ounce; dogs and cats ¹⁄₈ to 10 grs. with
jalap 10 to 30 grains.