For deep intramuscular injection the insoluble mercuric salicylate and the soluble bichloride, biniodide, and benzoate are the favorites. The former is insoluble in water or oil, and is used in 10 to 30 per cent. admixture with liquid paraffin or olive oil. According to Lascoff, it makes the best mixture if half per cent. of lanolin is added. The dose is \ to 1 1/2 grains (0.03-0.1 gm.), injected into the buttock once a week, or every five days, or in urgent cases every second day. More or less soreness, as of a bruise, may follow the injection for a day or two, and occasionally headache, languor, nausea, and diarrhea. The benzoate, dose 1 grain (0.06 gm.), and the bichloride and biniodide, dose 1/10 to 1/5 grain (0.006-0.012 gm.), are more readily absorbed, so must be administered every second day. The bichloride is irritating, and also destroys the needles. The advantages of the hypodermatic method are: the exact dosage, the cleanliness, and the close supervision of the patient which are gained by the necessarily frequent visits.

In comparing mercury with salvarsan, Schamberg and Kolmer found that in the test-tube salvarsan was more destructive to animal parasites and mercury more destructive to vegetable organisms.

The intravenous route is not much employed because of the danger of thrombosis or phlebitis. The dose recommended is 1/6 grain (0.01 gm.) of the bichloride in 2 1/2 drams (10 c.c.) of distilled water, or \ to 1 1/2 grains (0.03-0.1 gm.) of the benzoate in 1 per cent. normal saline. To avoid thrombosis Nixon mixes the 10 c.c. of bichloride solution with 10 c.c. of blood drawn into the syringe, and injects the mixture. Mercurialized human or horse serum is also employed, 1/50 or 1/25 grain (0.0012-0.0024 gm-) of the bichloride being added to about 1 ounce (30 c.c.) of serum.

For cerebrospinal syphilis, tabes, paresis, etc., the intraspinal injection of mercurialized human or horse serum may be employed in amounts representing 1/50 grain (0.0012 gm.) of mercuric bichloride. It may give the same sequelae as intraspinal salvar-sanized serum (see Salvarsan).

III. The Cathartics. (See under Cathartics.)

IV. Those with Special Uses, Other Than Those Mentioned

Mercury subsulphate (turpeth mineral), as an emetic in croup. Dose, 2 grains (0.13 gm.) for a child of six.

Calomel, in croupous laryngitis; 5 to 20 grains volatilized on a tin plate or in a teaspoon, and inhaled - not often employed at the present time. Calomel may be of value at the beginning of a course of diuresis. If it is absorbed, it tends to irritate kidney cells, but, as a matter of fact, most of it fails of absorption and passes out by the rectum. It is probable that much of the value of calomel in inducing diuresis is due to the relief of the splanchnic circulation through purging.

In malaria, Barlow uses bichloride intravenously, the dose being 1/4 grain (0.015 gm.) in 2/3 ounce (20 c.c.) of saline solution. He claims it to be especially useful as an adjunct to quinine, in the refractory cases.

The use of mercury succinimide, 1/5 grain (0.0012 gm.) every second day for 30 injections, has been recommended in tuberculosis, but has not proved curative.

Systemic Action Of Mercury Salts

After absorption mercury becomes generally distributed throughout the body, but is especially stored up in the liver. In its therapeutic use it has little direct action on any of the tissues; but an improvement in the blood and nutritional state is believed to follow repeated small doses.

Elimination

It is eliminated by the salivary glands, stomach, liver, kidneys, skin, colon, and rectum. It appears in the urine in three to twenty-four hours after ingestion, and in the feces after twenty-four hours (Lambert and Patterson). After subcutaneous injections for syphilis, Mironowitsch found more mercury in the sweat than in the urine. The major portion passes through the walls of the colon and upper rectum and may cause considerable irritation or actual colitis. Koldewijn applied mercurial ointment to cows, and was unable to find mercury in the milk; but Haas found that 1/32 grain (0.0005 gm.) of mercuric chloride given three times a day to the mothers of syphilitic infants had a slight but positive remedial effect on the nursing child. It is said that mercury has been detected in the tissues six months after its administration has been stopped.

Kidneys

Even after cathartic doses of a mercurial the metal has been found in the urine. Mercuric chloride has a special destructive action upon the epithelium of the convoluted tubules, and has been employed to produce experimental tubular nephritis. In acute poisoning there may be a violent exudative nephritis or nephrosis; in subacute or chronic poisoning there may be a diffuse nephritis, the destructive effects in the tubules being followed by changes in the glomeruli and increase of connective tissue. Foster reports a case of bichloride poisoning that died after forty-one days with the kidney lesion almost strictly confined to the tubular epithelium. The non-protein nitrogen rose to 238 mg. per 100 c.c. of blood, but there was no chloride or water retention. Calomel is frequently employed to aid other diuretics; but it probably acts by catharsis to relieve the kidneys, rather than by direct irritation of the kidney cells.

Toxicology Of Mercury

1. The mildest form of poisoning has for its prominent feature "mercurial stomatitis," or, as it is commonly called, "salivation." This is a not uncommon result of mercury salts administered as remedies, even a grain or two of calomel being sufficient in some cases to produce it. It is much more readily produced in nephritis than when the kidneys are unimpaired. In several instances the author has seen salivation in nephritis from two or three compound cathartic pills (each of which contains one grain of calomel).

The symptoms of "salivation" are: profuse flow of saliva, metallic taste, very foul breath, coated swollen tongue, soreness or ulceration of the gums or inside of the mouth, soreness of the tooth-sockets (test patient by having him hit teeth together), and loosening of the teeth. The profuse salivation may go on to inflammation of the salivary glands and necrosis of parts of the mouth and jaw. In addition, the patient feels ill and there may be headache, lassitude, muscular weakness, and diarrhea; occasionally there is constipation. As a prophylactic during the administration of mercury salts, and as treatment for mercurial stomatitis, a mouth-wash of a saturated solution of potassium chlorate with a little tincture of myrrh is recommended.