76 



SCIENCE 



[N. S. Vol. XLII. No. 1072 



categories: First, the development of new 

 apparatus and technique, thus insuring 

 progress in technical lines ; second, the ac- 

 cumulation of normal physiological data 

 regarding the metabolism and many physio- 

 logical factors of both men and animals, 

 such research being needed to supplement 

 the insufficient data secured in previous 

 investigations; and third, the comprehen- 

 sive, critical study of certain pathological 

 cases, notably diabetics. In connection 

 with the first of these lines of work there 

 has been not only the development of a 

 large amount of apparatus — for the greater 

 part of the apparatus used in the nutrition 

 laboratory has been there devised and con- 

 structed — but also an extensive comparison 

 of other methods in regular use, to deter- 

 mine their degree of accuracy and applica- 

 bility. 



The laboratory building is of special con- 

 struction, the main feature being the large 

 room devoted to calorimetric researches. 

 "With so delicate an apparatus as the calo- 

 rimeter, the effect of temperature environ- 

 ment is profound, and consequently this 

 room is provided with heating and cooling 

 devices by which the temperature may be 

 held constant. Researches with this appa- 

 ratus may therefore be conducted at any 

 time of the year without regard to the pre- 

 vailing temperature. 



As at present equipped, the calorimeter 

 laboratory has four calorimeters, all of 

 which may be used for studying the heat 

 production of the human body. Of these 

 the bed calorimeter has been most exten- 

 sively used for studying normal men and 

 women as well as in a long series of experi- 

 ments with severe diabetics. The inner 

 chamber of this apparatus is copper-waUed 

 and about 7 feet long and 3 feet wide, vary- 

 ing in height from 2 feet at the foot to 

 about 3^ feet at the head. The subject, 

 lying comfortably on a mattress, is slid into 



this chamber and the opening closed with a 

 large piece of plate glass, the closure being 

 made airtight by sealing with wax. The 

 ventilating current draws the air from this 

 chamber, forces it through sulphuric acid to 

 remove the water vapor given off by the 

 lungs and skin of the subject, and then 

 through soda lime to remove the carbon 

 dioxide. After pure oxygen has been added 

 to replace that used, the air returns to the 

 chamber to be rebreathed by the subject. 

 By weighing the soda lime containers at the 

 beginning and end of the experiment and 

 metering the oxygen admitted, we have a 

 direct measure of the carbon dioxide pro- 

 duced and the oxygen consumed. This is 

 the respiratory feature of the apparatus. 



The method of measuring the heat pro- 

 duction is of particular interest. The inner 

 chamber or copper box is surrounded by 

 several layers of material which provide 

 good insulation. Outside of this copper box 

 are two supplementary walls, the first of 

 zinc and the second of a one-inch layer of 

 cork. These walls are in each case three 

 inches from the inner wall, providing two 

 dead air spaces between the copper and the 

 zinc and the zinc and the cork, respectively. 

 The outside of the calorimeter is finished 

 with compo board. Thus, the apparatus is 

 of the refrigerator type of construction, 

 effectually preventing heat radiation. In 

 winter, houses are heated by passing hot 

 water through pipes. This small chamber, 

 or little house, would, unless cooled, become 

 uncomfortably warm from heat given off 

 by the body, and provision for cooling is 

 made by passing a current of cold water 

 through the chamber in fine serpentine 

 copper pipes. The temperature of the water 

 is recorded as it enters and leaves the 

 chamber. If the total weight of water 

 leaving the apparatus is measured the heat 

 brought away is readily computed by multi- 



