666 EXPERIMENT STATION RECORD. 



volume, and delivering aliquot samples of convenient size for analysis, is an appara- 

 tus designed and mad*; by Mr. O. S. Blakeslee, and appropriately designated by him 

 as a ' meter pump.' The essential parts for maintaining the air current and measur- 

 ing its volume are cylinders of steed. There are two pumps which work in unison. 

 Three steel cylinders are employed for each pump. The inner and outer cylinders 

 arc arranged concentrically, with an annular space 1.2 cm. in width between them. 

 This space is partly filled with mercury. Between the inner and outer cylinders, 

 which are stationary, plays a central cylinder, its lower portion being immersed in 

 the mercury. The central cylinder is closed at the top and is raised and lowered by 

 a walking beam The inner cylinder is also covered at the top, but through this 

 cover are two circular apertures opened and closed alternately by an automatic valve, 

 actuated by a compressed-air mechanism underneath. Connected with these aper- 

 tures are pipes passing downward through the inner cylinder. One serves to convey 

 the air, as it conies from the chamber, into the pump as the central cylinder rises. 

 As the cylinder falls the other pipe conveys the air outward, and thus plays the part 

 of a discharge pipe. The automatic valves open and close the inlets and discharge 

 pipes so that with each stroke of the inner cylinder the air is cut off at the proper 

 time. The length of the stroke of the cylinder is determined exactly by rods pro- 

 vided with stops, these rods playing through guides on two sides of each cylinder, 

 and by this arrangement the only variation is that which comes with the very slight 

 changes in the length of the rods due to changes of temperature. The air coming 

 from the discharge pipe escapes into the room, but by a special device the air of 

 each fiftieth stroke of each pump is diverted into a receptacle, from which it is being 

 constantly drawn for analysis." 



Ill the electrical check experiment a total of 3,017.4 calories of heat 

 was liberated in the chamber. The amount measured was 3,010.7 

 calories. In other words, the two values were practically identical. 



"In the alcohol tests the average amounts found by actual experiment were, for 

 carbon, 99.6 per cent, hydrogen, 100.6 per cent, and heat, 99.8 per cent of the theo- 

 retical amounts. It thus appears that this apparatus, when used for the analysis of 

 alcohol and the determination of its heat of combustion, gives results nearly, if not 

 quite, as accurate as are obtained by the ordinary laboratory methods." 



Of the two experiments with man, one was made in May, LS97, and 

 the other in January, 1898. The former is reported in much more detail 

 than the other. 



"The experiments with a man each continued dnring 8 days, during the last 4 

 days and 5 nights of which the subject was in the respiration chamber. The diet 

 during each experiment was uniform through the whole 8 days. The purpose of the 

 preliminary period of 1 days was to bring the body into at least approximate nitro- 

 gen and carbon equilibrium with the food and to make the determination of the 

 amounts of nutrients absorbed as nearly accurate as practicable The income and 

 outgo of nitrogen were determined during this period, which thus amounted to a 

 digestion and metabolism experiment. The metabolism of nitrogen, carbon, hydro- 

 gen, and energy was determined during the final period off days. 



"In one of the 2 experiments the man had as little muscular exercise as he could well 

 have with comfort. In the other he was engaged in quite active muscular exercise. 

 The external muscular work was expended in driving a dynamo which produced an 

 electric current. The latter was passed through a resistance coil, and the energy 

 was transformed into heat, which was measured with that given off from the body." 



The daily income and outgo of nitrogen and carbon and the calcu- 

 lated loss of protein and fat is shown in the following - table. 



