LECTURES. 



153 



This experiment was important in corroboratin<]j tlie fact that life 

 might often he sustained for long periods, even in limited quantities 

 of air, where animation was not temporarily suspended. 



On the other hand, at different times and under other circum- 

 stances, he had suifered more from air not nearly so much contami- 

 nated as it was in this instance, and adverted particularly to the fact 

 that the intensity of vitality was often very different in different indi- 

 viduals, and also in one and the same individual at different 

 times. To impress this upon the attention of the audience, an experi- 

 ment was then shown, in which a common candle, a wax candle, au 

 oil lamp, a spirit lamp, and a gas lamp, were kindled at tne same 

 level under a large glass shade, all communication with tlie external 

 atmo8])liere having "been cut off. In a short time the air became so 

 vitiated that the common candle ceased to burn. Subsequently the 

 wax candle was extinguished, then the oil lamp ; the spirit lamp 

 came next in order, and last of all, but long after the others had 

 ceased to burn, the gas lamp was also extinguished, struggling pre- 

 viously in the form of a long pale-blue flame. In the same manner 

 death took place among different individuals, even from the very same 

 causes, in very different periods of time, some sinking without a mur- 

 mur where the bystanders scarcely noticed the causes that deprived 

 them of life, while others sustained themselves throughout a long and 

 painful struggle. 



Dr. Reid then described the manner in which experiments on respi- 

 ration had been made with small quantities of air, and tlie peculiari- 

 ^ties of the apartments constructed at his lecture room at Edinburgh 

 'for researches on respiration and ventilation, where tlie amount of air 

 supplied to numbers, varying from one to two hundred and fifty, 

 could be precisely ascertained and controlled. Sometimes one or more 

 individuals were placed in an air-tight box, coutairiing a definite 

 amount of air. On other occasions one hundred individuals or up- 

 wards were placed in an air-tight room with a porous_ floor and a 

 porous ceiling, the cavities below and above communipating with 

 channels by which air could be made to enter and be withdrawn in 

 any required proportion. 



From these experiments and others tlie conclusion was drawn that 

 ten cubic feet per minute is an ample allowance of air for an adult — 

 far more than he generally has in ordinary habitations, but not more 

 than every ordinary structure should have the means of providing at 

 a minimum. Dr. Reid was prepared to admit that a less amount 

 would generally sustain health, but asserted that it would not give 

 the comfort and maintain the constitution in such good condition as 

 a larger allowance. In extreme atmospheres, -loaded with moisture 

 or charged with special im])urities or malaria, and at comparatively 

 elevated temperatures, there was no limit to the amount of increase 

 that proved grateful to particular constitutions. He had, in some 

 cases, given forty, fifty, and even a larger number of cubic feet per 

 minute with advantage, but there the velocity of the air acted essen- 

 tially as a cooling power from the great amount brought to affect the 

 body in a given time. Such velocity was not desirable where au 

 equivalent effect could be produced by cooling the air previously. But 



