A STUDY IN MORUID AXD NORMAL PHYSIOLOGY 25 



This is then divided by 497.603 to reduce it to pounds, and becomes U.0-327G lb. 

 A pound of water requires 19.20 heat units to vaporize it ; and 0.05276 X 79.25 = 

 4.181 ^ units of heat expended in process of vaporization in the box. The 

 same result will of course be obtained by dividing the 2G.255 by G.2789, since 

 497.603_g2^yy 

 79.25 

 In the fourth column of the tabulated report of the experiment, is given the 

 temperature of the water in the box at tlie commencement and at the end of 

 the time during which the animal was in the calorimeter; the difference, which 

 is stated at the bottom of the column, of course represents the gain of tem- 

 perature by the water, and in the present instance is 0.4. It is evident that the 

 metal of the calorimeter shares with the water in this increase of temperature, and 

 that this heat must be estimated. The most convenient form is to calculate first 

 the thermal equivalent of the calorimeter as the basis of experimentation. Thus, 

 in tile largest instrument employed in my experiments, there were 157 pounds of 

 water and 60 pounds of iron. The specific heat of water at the temperature of 60° 

 is very nearly 1.002, of iron 0.11o79, suppose t := 1. 



Q = w X t X sp. h. = 157 X 1 X 1.002 = 157.314 



Q = w X t X sp. h. = 60 X 1 X 0.11379 z= 6.8274 



The amount of heat required to raise calorimeter P F. 164.1414 units. 



In the experiment under consideration it is plain that 164.1414 x 0.4 = 65.6565 

 units = the amount of heat imparted to the calorimeter. 

 Finally the calculation is summarized as follows: — 



Heat given to air . . . . . . . . 2.2694 



Heat expended in vaporization . . . . . 4.181 



Heat given to calorimeter ...... 65.6565 



Total gain of heat in I5 hours, in excess of tliat lost by 



the apparatus 72.1069 



Hourly gain of heat, in excess of that lost by tlie appara- 

 tus, expressed in English units ..... 48.0713 



In many of the experiments an attempt was made not only to measure the 

 amount of heat given off, but also the production of carbon dioxide. The sample 

 of air taken from the box current was analyzed, and the amount of carbon dioxide 

 contained in it on being multiplied by the quotient for the box gave the total 

 amount (a) of carlion dioxide coming from the box. Then the amount of gas 

 contained in the sample of air analyzed multiplied by the quotient for the air gave 

 the quantity of the dioxide which entered the box (b). Subtracting these results, 

 b from a, the total elimination of carbonic acid by the animal became known. 



One of the most common methods employed in the determination of carbon dioxide 

 (CO.,) consists in conducting the evolved gas into a- solution of calcium hydrate, 

 and after allowing sufficient time for the amarplious calcium carbonates to become 

 crystalline, filtering it. After washing it is decomposed with an acid, and the 



4 March, 1880. 



