5o6 SCIENCE PROGRESS 



dentistry ; he received a patent irom Louis XVI. for his so- 

 called " mineral paste "for making porcelain teeth in 1790, and 

 in a book which he wrote declared that he had provided his 

 artificial teeth to no less than 12,000 persons. 



The introduction of porcelain teeth did not become general 

 until 1837, when their production was undertaken by a London 

 manufacturer named Claudius Ash. 



The Introduction of Nitrous Oxide (" Laughing Gas ") 



The year 1844 marks another stage in the history of dentistry, 

 for it was then that "laughing gas" was first used as a general 

 anaesthetic for a dental operation, though its anaesthetic pro- 

 perties had been surmised by Sir Humphry Davy many 

 years before. 



The story of its introduction for this purpose is of consider- 

 able interest. At a popular science lecture given at Hartford, 

 Conn., on the subject of nitrous oxide gas, a man named 

 Cooley was among those invited to inhale the gas in order to 

 show its effects ; taking some deep inspirations, he is said to 

 have become unconscious, falling to the ground and severely 

 injuring himself. 



A certain Dr. Horace Wells in the audience was much struck 

 by the peculiarity of the incident, and after the lecture arranged 

 with Dr. Colton, the lecturer, to come to his surgery and 

 administer the gas to him while he had a molar tooth extracted 

 by a Dr. Riggs. The following is a contemporary verbatim 

 report by the operator, who describes the operation in the 

 following words : 



" A few minutes after I went in 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 the bag of gas from Mr. 

 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 on 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, dis- 

 charged the blood from his mouth, and said : ' A new era in 



