Includes an account of Snow’s regulating inhaler, the first to control the amount of ether vapor by the patient. This pamphlet, which appeared in October 1847, was the second treatise on ether anesthesia, after Robinson who pubiished in March, 1847.
Snow first published a description and illustration of the regulating inhaler in Lond. med. Gaz., 1847, n.s. 4, 745-52, 923-29. 

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.

Snow’s chloroform inhaler.

Snow first became interested in cholera at Newcastle-on-Tyne during the epidemic of 1831-1832, and recurrent outbreaks of the disease gave him the opportunity to investigate it in detail. His paper on cholera, published shortly after his (extremely rare) 31-page pamphlet On the Mode of Communication of Cholera (1849)  contained his first demonstration of the specific nature of the disease, which he defined correctly as an infection of the alimentary canal transmitted by ingesting fecal matter from cholera patients, in most cases via contaminated water. Snow proved his theory of cholera transmission by collecting data on a large number of outbreaks and correlating them to local water supplies. He argued, based on his data, that cholera was caused by “a specific living, waterborne, self-reproducing cell or germ” (Dictionary of Scientific Biography)—a conclusion all the more remarkable in that it predated the germ theory of disease by over a decade.

Snow may have been motivated to contribute his paper to the London Medical Gazette because a review of his separately published pamphlet published in that journal on pp. 466-470 of the 1849 volume stated that he had not proved the contagious nature of cholera.

Publication of Snow's 31-page pamphlet on cholera preceded his paper in the London Medical Gazette by about one month. 

Snow attempted carbon dioxide absorption.

The second edition of Snow's book on cholera, with 162pp. compared to 31pp. in the first edition, incorporated the results of five more years of research, and contained so much additional material that it was essentially a new work. Snow set out his views that cholera was caused by a living organism, a belief later confirmed by Koch's discovery of the cholera vibrio in 1883. Snow included statistical surveys made during the great cholera epidemic of 1854, demonstarting that the number of cholera deaths in each area of southern London corresponded to the degree of contamination of the local drinking water. In this edition he told the famous story of the Broad Street pump for the first time, and included the famous spot map of the district showing the location of each pump and the fatal cholera cases. This was the first use of a spot map in epidemiology. Digital facsimile of the 1855 second edition from Google Books at this link.

Snow, the first specialist in anesthesiology, delivered Queen Victoria with the aid of chloroform in 1853 and 1857. This work was edited for publication after Snow's premature death by Richardson, who included a biography of Snow. Snow's final book, which consisted of 538pp. compared to only 88pp. in his first book on anesthesia published in 1847, put the administration of chloroform and ether on a scientific basis. Snow also investigated amylene, which he was the first to administer. Digital facsimile of William T. G. Morton's copy in the Countway Library of Medicine from the Internet Archive at this link.