He claimed to have administered the fumes of his alcoholic mixture to a Mrs. Allen, of Philadelphia, in 1842, and while under its influence he extracted a tooth without causing her pain. Collier’s lectures excited general attention at the time, and there is little doubt that they gave a fresh impetus to research on the subject of anæsthesia by inhalation. He must therefore be regarded as an important pioneer, who, had he given up his ideas of mesmerism and proceeded systematically with his plan of making the body insensible by inhaling the vapour of alcohol, would have had no one to dispute with him in priority. THE NITROUS OXIDE ERA Although, as already stated, Humphry Davy had discovered the anæsthetic properties of nitrous oxide as far back as the year 1800, forty-four years elapsed before his idea was put into practical use. [Sidenote: Colton lectures on nitrous oxide] On December 11th, 1844, Dr. G. Q. Colton, a well-known lecturer on popular scientific subjects in America, and a pupil of Professor Turner, of London, delivered a lecture at Hartford, Connecticut, during which he gave a demonstration of the action of nitrous oxide gas. Horace Wells, a dentist, then in practice in the same town, formed one of the audience. [Illustration: HORACE WELLS] [Sidenote: Wells makes his historic experiment] Among the persons who were invited by the lecturer to inhale the gas for the amusement of the audience was a man named Cooley, who wounded himself severely by falling against the benches, and only became aware of the fact when he saw the blood. Wells was greatly struck by this incident, and he determined to test the anæsthetic effects of the gas upon himself the next day by having a decayed upper molar extracted while under its influence. After the lecture he asked Dr. Colton if he would come to his house and administer the gas to him; and, on receiving his promise, he induced a Dr. Riggs to be the operator. The historic event is described by the latter as follows: “A few minutes after I went in, and, after conversation, Dr. Wells took a seat in the operating chair. I examined the tooth to be extracted, with a glass, as I usually do. Wells took a bag of gas from Dr. Colton and sat with it in his lap, and I stood by his side; he then breathed the gas until he was much affected by it: his head dropped back, I put my hand to his chin, he opened his mouth, and I extracted the tooth. His mouth still remained open some time. I held up the tooth with the instrument that the others might see it; they, standing partially behind the screen, were looking on. Dr. Wells soon recovered from the influence of the gas so as to know what he was about, discharged the blood from his mouth, and said, ‘A new era in tooth-pulling!’ He said it did not hurt him at all. We were all much elated, and conversed about it for an hour later.” [Illustration: “A NEW ERA IN TOOTH-PULLING”