Krahmer concluded from observations on himself, that the presence of silver in the system lessened oxygenation and the excretion of urea, of uric acid, and of the watery constituents of urine; the non-nitrogenous elements were, however, increased, and the sp. gr. rendered higher. If the administration of silver salts be continued beyond a certain point, cachexia sets in, appetite and digestion are impaired, catarrh and effusions take place, the temperature is lowered, and the action of the heart and lungs weakened. The general debility and emaciation are mainly dependent upon gastric irritation, but the drug seems to exert a special "alterative effect" on tissue-change. Dr. H. Wood classes it with "mineral astringents," Dr. Bartholow with "agents increasing waste," but I think it better placed among those that "moderate or retard nutritive processes" (Rabuteau). The recent observations of Roz-sahezzi show a very marked diminution of tissue-change and of weight, under the continued influence of small doses of nitrate. This occurred even while the animal was taking a good amount of food, and when no increased excretion could account for the loss; he thinks it indirect from impaired blood and muscle-condition.

He finds (as opposed to Bogolowsky) that small doses cause a rise in temperature, but agrees with Falck that large ones lower it.

When death has followed the long-continued use of the drug, the epithelial structures, and the solid tissues generally - the liver, heart, muscles, kidneys have been found in a state of "cloudy swelling" and fatty degeneration, and the metal has been detected in most parts of the body.

Fatal Dose (Acute Poisoning)

This varies with the gastric condition, period of vomiting, and of treatment, etc.: 30 gr. of nitrate have caused death in one case, while 1 oz. has failed to do so in another (that of Poumarede). Large doses have been neutralized by excess of natural mucus, or of albuminous food.

Synergists

As regards local effects, the nitrate is allied with irritants and caustics, such as iodine and arsenic. In its general action, especially in therapeutical doses, a resemblance may also be found with these medicines as well as with compounds of chlorine, bromine, and salts of bismuth, and in a less degree, of zinc. Some analogy with strychnia has been traced (Charcot).

Antagonists And Incompatibles

Sulphuric, hydrochloric, and tartaric acids and their compounds are chemically incompatible: also alkalies and their carbonates, astringent infusions, and lime-water; also creosote (v. p. 24). All soluble chlorides and cyanides are incompatible, since they precipitate an insoluble chloride of silver; most natural waters do so because they contain common salt: this salt is the best antidote to poisonous doses of the drug, and should be given freely so as. to cause emesis as well as to neutralize the poison.

Therapeutical Action (External)

Nitrate of silver may be applied either (1) as a caustic, (2) astringent and alterative, (3) counter-irritant, or (4) as a direct irritant.

1. Caustic. - Lupus. - In cases of tubercular and ulcerating lupus the "lunar caustic" is sometimes suitable, and in the hands of Hebra, Neumann, and others, has given good results. No ordinary application or simple pencilling will be of any service, for it will not extend deeply enough, but a well-pointed "stick" should be firmly pressed into the soft tissue, in various directions and until hard tissue is met with: this is an extremely painful process, and in my experience can seldom be thoroughly done except under chloroform. As a rule, I prefer the nitrates of mercury or of zinc, but silver has the advantage sometimes where the face is affected, because its action can be so precisely limited to the diseased part, and does not cause so marked a cicatrix. Dr. Piffard recommends fine needles to be coated with the caustic and passed into the growth, finding this to be less painful than Hebra's method. Soothing applications, such as poultices and lead lotions, should be made after the cauterization, which may require repetition once or even twice weekly for some time. M. Claude specially recommends the double iodide of silver and potash (internally) in lupus and skin-disorders.