“Twenty-five minims of chloroform produce only twenty-six cubic inches of vapor, and as one hundred cubic inches of air, at 60° Fahr., will take up fourteen cubic inches of vapor, and at 70° will take up twenty-four cubic inches, if fully saturated, it is quite possible that the air during inhalation may contain ten per cent. of the vapor, if means be not taken to prevent it. Under these circumstances, each hundred cubic inches of air would contain nearly ten minims of chloroform, and this might be taken into the lungs at once by a rather deep inspiration. The average quantity of chloroform present in the blood of an adult, when sufficiently insensible for a surgical operation, is eighteen minims, while twenty-four minims are as much as can be present in the system at one time with safety. The absorption of a little more than thirty minims would have the effect of causing death, even if it were equally diffused throughout the circulation. It must be evident, therefore, that to take ten minims of chloroform into the lungs at one inspiration, when insensibility is almost complete, must be attended with danger. “Robust persons, accustomed to hard work or violent exercise, are very apt to become affected with rigidity of the muscles and struggling, when nearly insensible from chloroform; and they often hold the breath for a time, and then draw a deep inspiration. It is under these circumstances that several of the accidents from chloroform have taken place, and extreme care is required to give the chloroform more than usually diluted with air, when this state of unconscious struggling and rigidity occurs. “The most important point to attend to, in the exhibition of chloroform, is to insure that the vapor shall be sufficiently diluted with air during the whole process of inhalation. This may be effected with a suitable apparatus and proper attention, or if an inhaler be not at hand, the chloroform should be diluted with one or two parts by measure of rectified alcohol. One or two drachms of this may be placed on a hollow sponge, and repeated when required. The spirit has the effect of limiting the quantity of chloroform which rises in vapor, while very little of the diluent is inhaled, since, from its lower volatility, the greater part of it remains on the sponge or handkerchief employed to exhibit the chloroform.