Pigeons are the animals which Dr. Richardson most employs for experiments on antes thetic agents generally. They pre,sent various advantages over most other animals; one cf the most important being that they die with singular readiness under the influence of these agents. On exposing three pigeons to the action of the vapor of a dram of chloro form, bichloride of methylene, and tetrachloride of carbon, the peculiarity in the action -of the bichloride is the absence, in the sleep it produces, of the so-called second degree cif narcotism. The bird glides from the first degree directly into the third, or that of absolute insensibility. The bichloridc enters the circulation freely, and sustains the insensibility so well, that intervals of many minutes may be allowed to pass without readministration; while, front its being transformed altogether into vapor at a tempera ture lower than that of the body, it can be more readily eliminated from the system than chloroform, or tetrachloride of carbon, when its administration is withheld. On ani mals it acts more evenly on the re,spiration and circulation than any other of the various substances which Dr. Richardson has tried; and the only drawback yet observed is, that it sometimes produces vomiting; but this misadventure, so ftu. as we know, has not yet been observed when it has been administered to the human subject, and pigeons are known to vomit on slight provocation. The numbers of the respirations and of the pulse rise and fall together, which " is a good point, because there is no condition more perilous than disturbed balance of the circulating and respiratory systems." All anwetheties given by inhalation after a certain dose destroy life; but that the -destructive power of this new agent is less than that of either chloroform or tetrachloride ,of carbon, seems proved.
On trying the vapor upon himself, after ascertaining that it could be safely given to the lower animals, Dr. Richardson inhaled it until it produced insensibility. " I found the vapor very pleasant to breathe and little irritating, while drowsiness came on and unconsciousness without any noise in the head or oppression. I recovered also, as the animals seemed to recover, at once and completely. I felt as though I had merely shut my eyes, and had opened them again. In the mean time, I had, however, performed certain acts of a motor kind unconsciously; for I inhaled the vapor in the laboratory, and there went to sleep, but I awoke in the yard adjoining. This was on Sept. 28 last, when I inhaled from a cup-shaped sponge. Since then, I have inhaled the vapor in smaller quantities from several instruments, with the effect of proving that there is little .difference required for its administration and that of chloroform. A little more bichlo ride required in the earlier stages than would be required if chloroform were being used, -the fluid being more vaporizable. One dram of bichloride to 40 minims (ids of a dram)
-of chloroform represents the difference required; but when the narcotism is well set up, less of the bichloride is required to sustain the effect." The materials on which this article is based are taken from a lecture delivered by Dr. Richardson on Oct. 8, 1867. In an address on antesthetics by Dr. Tidy, published rin the Briti,th Medical Journal, Jan. 4, 1879, it is mentioned that Mr. Morgan, a dentist, has " administered methylene 1800 times to persons of all ages, and for periods varying from a few minutes to three-quarters of an hour, without a single accident. He also -rega-rds it as safer than chloroforrn, and speaks of the rapidity with which it effects complete unconsciousness, as a rule two minutes only being needed; the rapidity of recovery, from one to three minutes only being required for the anmsthesia to pass away; and lastly, the rapidity with which consciousness may be abolished, if it return during the operation—as the chief points in its favor. The cause of death from its administra tion is syncope, not coma; hence, a bloodless condition of the lips—a point easily to be noticed—is the principal intlication of danger." On the other hand, the preliminary report on the action of antesthetics presented to the committee of the British medical association, and published in the same number of the Journal, does not speak so favorably of methylene. The so-called bichloride of methylene, it is alleged, has no definite and constant boiling point, and therefore appears to be a mixture. The formula, as now generally used, CH,C1,, ShOWS it to be a com pound of chloride of methyl and chloroform (CH3C1-1- CHOY. With frogs under methylene it was found that the heart became rapidly affected and soon stopped. With rabbits, respiration rapidly deteriorated and stopped while the heart was still beating. In an experiment with artificial respiration and exposure of the heart, the heart was weakened and soon stopped, but not as rapidly as with chloroform. As in the case of chloroform, the right ventricle became enormously distended, the first.sig-n of paralysis being the commencement of the distension. [Ether does not affect the heart.] The ..experimenters found that as anwsthetics, 1,9obutyl chloride (C6119) and ethiclene dichloride 1r2H4C13) combine the advantages of speed and safety, and are therefore preferable to methylene.
Chloride of methyl, the first of the compounds derived by substitution from hydride of methyl, has, according- to good authorities, also valuable remedial qualities. Half an ounce of it, diluted with water, and with the addition of a little sugar, acts as a pleasant but potent intoxicator. In smaller doses, it might be useful as a soothing and refrigera ting agent.