On the inhalation of the vapour of ether in surgical operations.

I have spoken of a knowledge of the strength of the vapour as being essential to a correct determination of the state of the patient at all times: and this brings us to the apparatus for the administration of the vapour, as, without a suitable one, the proportions of air and of vapour cannot be determined. I had the honour of shewing that these proportions could be easily and precisely controlled by means of the temperature* and of introducing an inhaler, by which the quantity of vapour in the air the patient breathes can be accurately regulated. It is made of metal, the best conductor of caloric, and placed in contact with water, the best and most convenient regulator of temperature; and, consequently, we are enabled to avail ourselves of the law which determines the quantity of vapour of ether that air will take up, and hold in suspension at various temperatures; in order to regulate the strength of the vaporized air as we wish. The opportunity was afforded me of using the apparatus soon after it was made, very frequently, in St. George's Hospital, and I believe that this was the first institution in which the vapour of ether was constantly applied with uniform and complete success in surgical operations. Several alterations in the details of the instrument were made, after it was delineated in the medical journals in the