242 Dr. W. Marcet and Mr. R. B. Floris. An Experimental 



difference is only one of 378 per cent., and the mean difference did 

 not exceed 34 calories on 34,462, amounting- to O'l per cent. only. It 

 may therefore be concluded that the present calorimeter has proved 

 itself very accurate for the determination of the heat produced by 

 the combustion of a given volume of hydrogen gas ; and, conse- 

 quently it can be accepted as equally reliable for the correct estima- 

 tion of the heat radiated from the human body or from that of a 

 fairly Jarge animal. 



" An Experimental Enquiry into the Heat given oufc by the 

 Human Body." By W. MARCET, M.D., F.R.S., and R. B. 

 FLORIS, F.C.S. Received March 10, Read April 28, 

 1898. 



(From the Physiological Laboratory of University College, London.) 



Dr. Marcet's calorimeter having been fully described in the previous 

 paper, the present conjoint authors now submitted themselves to 

 experiment, one of them remaining shut up in the chamber, usually 

 for the space of an hour, while the other was engaged outside to 

 regulate the temperature of the chamber and note the readings of 

 the thermometers. 



When breathing was carried on inside the calorimeter, it might 

 be thought that the air of the chamber became too full of C0 2 or too 

 deficient in oxygen for the purposes of respiration. Such, however, 

 was not the case, and no discomfort whatever was experienced in the 

 course of an hour's incarceration. It is easy to calculate from a con- 

 sumption of, say, 26'488 grams of O per hour that supposing the 

 calorimeter to be absolutely air-tight, a condition which was not 

 actually realised, there would be a fall of oxygen, after one hour 

 spent in the calorimeter, equal to a reduction of pressure from 

 760 mm. to 668 mm., and this would correspond to an elevation of 

 about 7000 feet (2135 metres) above the sea level. Such an altitude 

 would certainly not be trying to the respiration. 



The experiment was carried out as follows in every instance: 



Previous to entering the chamber the subject of the experiment 

 sat down in the laboratory to rest, in many instances taking his 

 temperature, sublingual, with a clinical thermometer. 



In the meantime a weight of ice varying between 10 Ibs. and 

 15 Ibs. (4'5 to 6'8 kilograms), according to circumstances, was cut 

 into blocks about 2 or 3 inches diameter, and placed in the ice holder, 

 where the blocks were disposed as much as possible in a position to 

 allow the air from the agitator to circulate freely between them. A 

 temporary receiver for the water from the melting ice was hung to a 



