The bismuth (bismuthum) salts commonly employed are the subcarbonate and the subnitrate, which are white, and the sub-gallate, which is yellow. Dose, 30 grains (2 gm.). The sub-nitrate is crystalline, the subcarbonate and the subgallate are amorphous. They are insoluble in water, are very slightly astringent, and resemble in their action the soothing salts of zinc. But their chief use is in the alimentary tract, where they do not form irritant compounds. The milk of bismuth (magma bis-muthi), dose, 3j (4 c.c.), is also official.

They act in a purely mechanical manner as protectives and demulcents to the mucous membrane of both stomach and bowels. It has been ascertained that if given before irritant emetics, they can prevent vomiting. The author has in a number of instances given bismuth subnitrate with a test-breakfast, and has usually at the end of the hour found a much lessened secretion or acidity. In a few cases the gastric secretion was not changed by the bismuth. It is noteworthy that at the end of the test-breakfast hour the bismuth salt was uniformly mixed with the extracted stomach contents, and that it had changed from a heavy powder to a flocculent substance that settled slowly with the food. Several hours after its administration to dogs the author found the bismuth subnitrate in this same flocculent state, and coating the mucous membrane very uniformly as far as the ileocecal valve. In the colon the bismuth salt becomes black from the formation of the sulphide or from reduction, and renders the stools black. As the sulphide forms hard crystals, it sometimes acts as an irritant.

The bismuth salts have come into very extensive use in x-ray work, their opacity to the rays making it easy to obtain pictures of the whole alimentary tract. The subcarbonate, the oxide, and the oxychloride are employed for this purpose by mouth or rectum, in amounts of 2 to 4 ounces (60-120 gm.), mixed with zoolak, buttermilk, thick soup, etc. The subnitrate is no longer employed in these large amounts, as a number of cases of bismuth and nitrite poisoning have occurred from its use. B oehme showed that bismuth subnitrate, when mixed with human feces, liberated nitrites.

In one x-ray case of the author's two very large bismuth balls formed in the colon and had to be broken up in the rectum before they could be extracted.

Toxicology

From the local application to extensive burns, from the injection into tuberculous sinuses, and from the use of it for x-ray pictures, bismuth has been the cause of poisoning.

Its symptoms resemble largely those of poisoning by the other heavy metals, and are: salivation and stomatitis, with a black, violet, or blue-gray line on the gums, nausea, vomiting, diarrhea, signs of kidney and colon irritation, convulsions, and collapse. Baehr and Mayer found considerable amounts of bismuth in liver, spleen, kidneys, and large intestine, and Rosenbloom found it in the urine. Davis and Kaufmann (1910) report a black line on the gums in 6 out of 25 cases in which bismuth had been injected into tuberculous sinuses or joints. One fatal case occurred from less than one ounce of the 33 per cent. paste. For such poisoning Beck, who was the originator of the bismuth treatment for sinuses, recommends to flood the sinus or cavity with warm olive oil and let it remain for twenty-four hours, and to wash the sinus with olive oil daily thereafter until the symptoms have subsided. He advises that the gums should be watched for the blue or black line, which is the first sign of poisoning.

Therapeutics

Beck's method of treatment of chronic sinuses or tuberculous cavities is to inject, not oftener than once a week, a 33 per cent. paste of bismuth subnitrate with vaseline. He advises against it in acute cases, or when fresh surfaces have been opened up by probing or cutting.

Internally, the insoluble bismuth salts are used: (1) To check nausea, vomiting, and gastric irritation, as in ulcer, marked hyperchlorhydria, and gastric intolerance. (2) To check intestinal irritation, either that of fermentative diarrhea or that from inflammation of small intestine or colon. The soluble bismuth salts, such as the citrate, have no value in medicine unless the bismuth is precipitated from them in the alimentary tract.

Of the "milk of bismuth," a white suspension, Hulse (1910) reports that in 21 infants with gastro-enteritis it passed through the alimentary tract unchanged and without effect; while inside of twenty-four hours bismuth subnitrate resulted in diminished blood and mucus and fewer stools, and showed by the dark color of the stools that it had undergone change.