Appearing in March, 1847, this was Snow's first publication on anesthesia. It contains the first description and illustration of his regulating inhaler, the first such device to control the amount of ether vapor received by the patient.
When ether anesthesia was introduced to England in late 1846 Snow immediately began experimenting with the process, and eventually became the first physician to limit his practice to anesthesiology. As the earliest specialist in clinical anesthesiology, Snow was also the first to perform experiments on the physiology of the anesthetized state, the results of which laid the foundations for the development of anesthesiology as a science. In the present paper Snow noted that the amount of ether vapor absorbed by air varied according to air temperature and provided a table of the proportion of ether to air at temperatures ranging from 38 to 90 degrees Fahrenheit.