No doubt these facts throw much light on the very irregular action of calomel in different persons and under various conditions, in doses which may be very small or very large. We can easily understand how, when the stomach secretes no gastric juice and when the salts of the blood have been greatly reduced in quantity by watery purging as in cholera, the calomel may pass through the alimentary canal unchanged, insoluble and inactive, or exert a doubtful topical action only.
The present writer's own experience—when he was a medical student, and when fully impressed by the sincere and logical teachings of Doctor Cooke, who, however halting and hesitating may have been his manner or unadorned his style of lecturing, always commanded the fixed attention and highest respect of his pupils—soon opened his eyes to the faults in the theory of the professor.
On one occasion, having been brought into a somewhat febrile condition by fatigue in a botanical excursion in hot weather, and having full faith in the statements of Doctor Cooke to the effect that calomel was of all antifebrile remedies the best, and that while a small dose of calomel might prove irritating a good large dose "would sometimes act like an opiate," he took a one drachm dose in full confidence. But instead of the soothing, curative effect he had been led to expect, vomiting and severe irritation of the stomach resulted, so much so that no food but boiled milk could be tolerated for a week or so afterward. Shaken in his faith by his first experience, but not yet convinced of the error of the doctrine of his respected preceptor, the second trial of a drachm dose on a similar occasion completely satisfied him that something wrong had crept into the theory and practice of the honored professor.
Doctor Cooke's only fear in his heroic use of calomel was that it would salivate. But for this untoward influence, he said, one might do almost anything with it. That this substance which, in cases of cholera, he administered so largely with no signs of irritation or salivation, until the patient was in a convalescent state, should sometimes in much smaller doses prove an irritant poison, he did not understand. A quotation from Doctor Yandell's Memoir, Page 7, illustrates this: "In some cases of fever Doctor Cooke administered a drachm of calomel at a dose, and repeated it until the patient had taken in twenty-four hours as much as two hundred and forty grains. A young lady was thus treated in 1826. After this quantity had been given she seemed much relieved, but to avert the danger of salivation he thought it prudent to administer jalap and cream of tartar. At night they were thrown up, without producing any purgative effect. She then took a drachm of calomel, and repeated it until she had taken five doses in the course of the night and morning, with the same fine effect in producing abundant bilious discharges, and a remarkably good effect on the symptoms generally." Still uneasy about ptyalism, he gave her cream of tartar all day, but at night it was thrown up as before, without moving the bowels. "My fears of the consequence of giving the only medicine which offered any prospect of saving her," he adds, "held my hand, and she continued to vomit till death relieved her. I reproached myself on her account afterward, and felt conscious that fear of a remote and uncertain evil had induced me to stand and see her die without doing all I might have done. I was convinced she would not have died had the calomel been continued."
After she had thus taken more than an ounce of calomel he honestly believed that he had not given her enough of this medicine! Entirely ignoring the action of the cream of tartar in bringing this substance partly into the condition of a soluble irritant poison!
To convince myself of this decomposing action of cream of tartar on calomel, I placed about a drachm of calomel in each of two small beaker glasses. In the one I put pure distilled water, in the other I added to the water about a drachm of cream of tartar. Heating them to about blood heat and allowing them to stand for a few hours, I filtered both liquids from the undissolved calomel. Ammonium sulphide, added to the filtered fluids, threw down from that which contained the cream of tartar a sensible amount of dark mercurial sulphide, while that which contained pure water gave no notable reaction. Evidently the cream of tartar had caused the decomposition of some of the insoluble calomel and had produced a soluble mercurial compound. All soluble compounds of mercury are active poisons in small doses, while, as was fully proven by Doctor Cooke's extraordinary practice with this substance, pure unchanged calomel is one of the most insoluble substances. Consequently it sometimes proved harmless in very large doses, as was the case when the copious watery discharges of cholera had removed most of the salts of the blood.
The Doctor took no note of possible agencies which might make his master remedy occasionally poisonous, and scouted the careful practice of some of the older physicians in causing their patients to abstain from the use of common salt while taking calomel, a recommendation based upon valid experience, no doubt, which science has verified.
The Doctor rose to two ounces, or tablespoonful doses, during the prevalence of Asiatic cholera in Lexington, but he did not confine this treatment to that fearful disease. The present writer has preserved one of the last of his mammoth doses—one of a dozen of the same weight (about an ounce)—which he prescribed for a medical student of the session of 1836–37, the subject of pneumonia, and who took eleven such doses in regular succession before he died.
In Doctor Cooke's earlier practice, and in the treatment of less severe cases, he relied greatly on his famous pills—well known in the region of Lexington as "Cooke's Pills"—composed of equal parts of calomel, aloes, and rhubarb; or on tincture of aloes and the lancet, with the occasional use of a few other remedies. These constituted his sole armament with which to encounter disease. For he was a man of the strictest and most earnest honesty, sincerity, and zeal, and withal so wedded to his logical convictions that he would at any time have died a martyr to his well-matured beliefs. Indeed, according to the testimony of his friend, the late Lunsford P. Yandell, he seems thus to have been to some extent a martyr to his own theory and practice.
On Page 22 of Doctor Yandell's Memoir of Doctor Cooke, we are informed that "his practice on himself was of the same heroic character that he pursued with his patients. He bled himself at once copiously and repeated the operation again and again as symptoms appeared to him to demand it, at the same time keeping up purgation with calomel. Exposed as he was on his farm, these attacks became frequent and his constitution, naturally enfeebled by increasing years, at length gave way under them."