FOODS ANIMAL PRODUCTION. 471 



The chamber is further provided with 2 fans which thoroughly mix 

 the air and are so arranged that the current is not unpleasant to the 

 person experimented upon. A vessel containing ice is suspended in 

 the chamber and the water formed by the melting ice is collected in 

 flasks suitably arranged. Comparatively little of the heat in the 

 chamber is lost, since it is reflected from the walls. The heat gener- 

 ated causes the ice to melt and the amount of heat can be calculated 

 from the amount and temperature of the water produced. In experi- 

 ments due allowance is made for the heat generated by the revolution 

 of the fans, and other necessary corrections are introduced. 



Experiments to test the accuracy of the apparatus were made by 

 introducing a jar of hot water into the chamber or by burning hydrogen 

 gas. From these the author concludes that the calorimeter is very 

 accurate. The calorimeter is so arranged that the respiratory products 

 may be collected outside the chamber for analysis. 



An experimental inquiry into the heat given out by the human 

 body, W. Marcet and E. B. Floris (Proc. Foi/. Soc. [London], 63 

 (1898), No. 396, pp. 242-255). — Using the calorimeter described above, 

 the authors made a number of experiments with men of various ages. 

 In some of the experiments the authors themselves were the subjects. 

 In several instances the respiratory products were collected for analy- 

 sis. The air was inspired through the nose and expired through the 

 mouth, a face piece with suitable tubes being worn. The usual plan 

 was to collect the air expired for periods of twenty minutes to half an 

 hour throughout the experiment. The author believes this gives a 

 means of accurately determining the con position of the air expired 

 while in the calorimeter, as the subject remains at rest. In one experi- 

 ment the total respired air was collected and it was found that the 

 volume expired in half an hour was proportional to the volume expired 

 in one hour. The experiments were generally of an hour's duration 

 and were made before and after eating and varied in other ways. The 

 results are summarized as follows: 



"(1) The amount of heat given out from the human body when tested on 2 succes- 

 sive half hours is found to be the same when the means of the calories are taken, 

 although in each separate experiment the heat emitted may vary to some slight 

 extent. 



"(2) The heat emitted by the same person varies, and the extent of this variation 

 is "wider in sonic subjects tlian in others. Thus, in one case the calories emitted in 

 one hour from 26 experiments varied from 122,121 t<» 80,639, or by 33.9 per cent of the 

 larger figure. In 21 experiments with another subject they varied from 106,830 to 

 80,985, or by 24.2 per cent; and with a third subject in 11 experiments from 137,078 

 to 111,754, or by 18.5 per cent. 



"(3) As a fact, irrespective of theory, the mean number of calories found from 3 

 different persons, under similar circumstances of food, etc., corresponding to 1 gm. 

 of oxygen absorbed from the air, was the same, and can be stated in round numbers 

 at 4,000. Had more experiments been done fasting, this figure would have shown a 

 slight tendency to fall. 



"(4) Although the mean calories per individual for 1 gm. oxygen absorbed under 

 similar circumstances of food, etc., are the same, still, in the experiments taken sin- 

 gly, the number of calories corresponding to 1 gm. oxygen absorbed vary, and this 



