Part 1

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Respiration Calorimeters for Studying the Respiratory Exchange and Energy Transformations of Man

BY

FRANCIS G. BENEDICT and THORNE M. CARPENTER

WASHINGTON, D. C. PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON 1910

CARNEGIE INSTITUTION OF WASHINGTON PUBLICATION NO. 123

The Lord Baltimore Press BALTIMORE, MD., U. S. A.

PREFACE.

The immediate development and construction of suitable apparatus for studying the complicated processes of metabolism in man was obviously the first task in equipping the Nutrition Laboratory. As several series of experiments have already been made with these respiration calorimeters, it is deemed advisable to publish the description of the apparatus as used at present. New features in the apparatus are, however, frequently introduced as opportunity to increase accuracy or facilitate manipulation is noted.

We wish here to express our sense of obligation to the following associates: Mr. W. E. Collins, mechanician of the Nutrition Laboratory, constructed the structural steel framework and contributed many mechanical features to the apparatus as a whole; Mr. J. A. Riche, formerly associated with the researches in nutrition in the chemical laboratory of Wesleyan University, added his previous experience in constructing and installing the more delicate of the heating and cooling devices. Others who have aided in the painstaking construction, testing, and experimenting with the apparatus are Messrs. W. H. Leslie, L. E. Emmes, F. L. Dorn, C. F. Clark, F. A. Renshaw, H. A. Stevens, Jr., Miss H. Sherman, and Miss A. Johnson.

The numerous drawings were made by Mr. E. H. Metcalf, of our staff.

BOSTON, MASSACHUSETTS, _August 10, 1909._

CONTENTS.

PAGE

Introduction 1

Calorimeter laboratory 3 General plan of calorimeter laboratory 3 Heating and ventilating 7

The calorimeter 10 Fundamental principles of the apparatus 10 The calorimeter chamber 11 General construction 14 Prevention of radiation 17 The thermo-electric elements 19 Interior of the calorimeter 20 Heat-absorbing circuit 22 Thermometers 26 Mercurial thermometers 26 Electric-resistance thermometers 28 Air-thermometers 28 Wall thermometers 29 Electrical rectal thermometer 29 Electric-resistance thermometers for the water-current 29 Observer's table 31 Connections to thermal-junction systems 33 Rheostat for heating 34 Wheatstone bridges 34 Galvanometer 35 Resistance for heating coils 35 Temperature recorder 36 Fundamental principle of the apparatus 38 The galvanometer 39 The creeper 40 The clock 42 Installation of the apparatus 42 Temperature control of the ingoing air 43 The heat of vaporization of water 44 The bed calorimeter 45 Measurements of body-temperature 48 Control experiments with the calorimeter 50 Determination of the hydrothermal equivalent of the calorimeter 52

General description of the respiration apparatus 54 Testing the chamber for tightness 54 Ventilation of the chamber 54 Openings in the chamber 55 Ventilating air-current 57 Blower 57 Absorbers for water-vapor 58 Potash-lime cans 60 Balance for weighing absorbers 61 Purification of the air-current with sodium bicarbonate 63 Valves 63 Couplings 64 Absorber table 65 Oxygen supply 67 Automatic control of oxygen supply 69 Tension equalizer 71 Barometer 72 Analysis of residual air 73 Gas-meter 75 Calculation of results 76 Analysis of oxygen 76 Advantage of a constant-temperature room and temperature control 77 Variations in the apparent volume of air 77 Changes in volume due to the absorption of water and carbon dioxide 78 Respiratory loss 78 Calculation of the volume of air residual in the chamber 79 Residual analyses 80 Calculation from residual analyses 80 Influence of fluctuations in temperature and pressure on the apparent volume of air in the system 83 Influence of fluctuations in the amounts of carbon dioxide and water-vapor upon residual oxygen 83 Control of residual analyses 84 Nitrogen admitted with the oxygen 84 Rejection of air 85 Interchange of air in the food aperture 85 Use of the residual blank in the calculations 86 Abbreviated method of computation of oxygen admitted to the chamber for use during short experiments 88 Criticism of the method of calculating the volume of oxygen 89 Calculation of total output of carbon dioxide and water-vapor and oxygen absorption 91 Control experiments with burning alcohol 91 Balance for weighing subject 93 Pulse rate and respiration rate 95 Routine of an experiment with man 96 Preparation of subject 96 Sealing in the cover 97 Routine at observer's table 97 Manipulation of the water-meter 98 Absorber table 99 Supplemental apparatus 100

ILLUSTRATIONS.

PAGE

Fig. 1. General plan of respiration calorimeter laboratory 4

2. General view of laboratory taken near main door 4

3. General view of laboratory taken near refrigeration room 4

4. General view of laboratory taken near temperature recorder 4

5. View of laboratory taken from entrance of bed calorimeter 4

6. Plan of heating and ventilating the calorimeter laboratory 6

7. Horizontal cross-section of chair calorimeter 11

8. Vertical cross-section of chair calorimeter 12

9. Vertical cross-section of chair calorimeter from front to back 13

10. Photograph of framework of chair calorimeter 14

11. Photograph of portion of framework and copper shell 14

12. Cross-section in detail of walls of calorimeter 16

13. Detail of drop-sight feed-valve and arrangement of outside cooling circuit 18

14. Schematic diagram of water-circuit for the heat-absorbers of the calorimeter 22

15. Detail of air-resistance thermometer 28

16. Details of resistance thermometers for water-circuit 30

17. Diagram of wiring of observer's table 32

18. Diagram of rheostat and resistances in series with it 36

19. Diagram of wiring of differential circuit with shunts used with resistance thermometers for water-circuit 38

20. Diagram of galvanometer coil, used with recording apparatus for resistance thermometers in water-circuit 40

21. Diagram of wiring of circuits actuating plunger and creeper 41

22. Diagram of wiring of complete 110-volt circuit 41

23. Temperature recorder 42

24. Detailed wiring diagram showing all parts of the recording apparatus, together with wiring to thermometers 42

25. Section of calorimeter walls and portion of ventilating air-circuit 43

26. Cross-section of bed calorimeter 46

27. Diagram of ventilation of the respiration calorimeter 57

28. Cross-section of sulphuric acid absorber 59

29. Balance for weighing absorbers 62

30. Diagram of absorber table 66

31. Diagram of oxygen balance and cylinders 68

32. The oxygen cylinder and connections to tension equalizer 70

RESPIRATION CALORIMETERS FOR STUDYING THE RESPIRATORY EXCHANGE AND ENERGY TRANSFORMATIONS IN MAN.

INTRODUCTION.

The establishment in Boston of an inquiry into the nutrition of man with the construction of a special laboratory for that purpose is a direct outcome of a series of investigations originally undertaken in the chemical laboratory of Wesleyan University, in Middletown, Connecticut, by the late Prof. W. O. Atwater. Appreciating the remarkable results of Pettenkofer and Voit[1] and their associates, as early as 1892 he made plans for the construction of a respiration apparatus accompanied by calorimetric features. The apparatus was designed on the general ventilation plan of the above investigators, but in the first description of this apparatus[2] it is seen that the method used for the determination of carbon dioxide and water-vapor was quite other than that used by Voit. Each succeeding year of active experimenting brought about new developments until, in 1902, the apparatus was essentially modified by changing it from the open-circuit type to the closed-circuit type of Regnault and Reiset. This apparatus, thus modified, has been completely described in a former publication.[3] The calorimetric features likewise underwent gradual changes and, as greater accuracy was desired, it was found impracticable to conduct calorimetric investigations to the best advantage in the basement of a chemical laboratory. With four sciences crowded into one building it was practically impossible to devote more space to these researches. Furthermore, the investigations had proceeded to such an extent that it seemed desirable to construct a special laboratory for the purpose of carrying out the calorimetric and allied investigations on the nutrition of man.

In designing this laboratory it was planned to overcome the difficulties experienced in Middletown with regard to control of the room-temperature and humidity, and furthermore, while the researches had heretofore been carried on simultaneously with academic duties, it appeared absolutely necessary to adjust the research so that the uninterrupted time of the experimenters could be given to work of this kind. Since these experiments frequently continued from one to ten days, their satisfactory conduct was not compatible with strenuous academic duties.

As data regarding animal physiology began to be accumulated, it was soon evident that there were great possibilities in studying abnormal metabolism, and hence the limited amount of pathological material available in Middletown necessitated the construction of the laboratory in some large center.

A very careful consideration was given to possible sites in a number of cities, with the result that the laboratory was constructed on a plot of ground in Boston in the vicinity of large hospitals and medical schools. Advantage was taken, also, of the opportunity to secure connections with a central power-plant for obtaining heat, light, electricity, and refrigeration, thus doing away with the necessity for private installation of boilers and electrical and refrigerating machinery. The library advantages in a large city were also of importance and within a few minutes' walk of the present location are found most of the large libraries of Boston, particularly the medical libraries and the libraries of the medical schools.

The building, a general description of which appeared in the Year Book of the Carnegie Institution of Washington for 1908, is of plain brick construction, trimmed with Bedford limestone. It consists of three stories and basement and practically all the space can be used for scientific work. Details of construction may be had by reference to the original description of the building. It is necessary here only to state that the special feature of the new building with which this report is concerned is the calorimeter laboratory, which occupies nearly half of the first floor on the northern end of the building.

FOOTNOTES:

[1] Pettenkofer and Voit: Ann. der Chem. u. Pharm. (1862-3), Supp. Bd. 2, p. 17.

[2] Atwater, Woods, and Benedict: Report of preliminary investigations on the metabolism of nitrogen and carbon in the human organism with a respiration calorimeter of special construction, U. S. Dept. of Agr., Office of Experiment Stations Bulletin 44. (1897.)

[3] W. O. Atwater and F. G. Benedict: A respiration calorimeter with appliances for the direct determination of oxygen. Carnegie Institution of Washington Publication No. 42. (1905.)

CALORIMETER LABORATORY.

The laboratory room is entered from the main hall by a double door. The room is 14.2 meters long by 10.1 meters wide, and is lighted on three sides by 7 windows. Since the room faces the north, the temperature conditions are much more satisfactory than could be obtained with any other exposure. In constructing the building the use of columns in this room was avoided, as they would interfere seriously with the construction of the calorimeters and accessory apparatus. Pending the completion of the five calorimeters designed for this room a temporary wooden floor was laid, thus furnishing the greatest freedom in placing piping and electric wiring beneath the floor. As fast as the calorimeters are completed, permanent flooring with suitably covered trenches for pipes is to be laid. The room is amply lighted during the day, the windows being very high, with glass transoms above. At night a large mercury-vapor lamp in the center of the room, supplemented by a number of well-placed incandescent electric lights, gives ample illumination.

GENERAL PLAN OF CALORIMETER LABORATORY.

The general plan of the laboratory and the distribution of the calorimeters and accessory apparatus are shown in fig. 1. The double doors lead from the main hall into the room. In general, it is planned to conduct all the chemical and physical observations as near the center of the laboratory as possible, hence space has been reserved for apparatus through the center of the room from south to north. The calorimeters are on either side. In this way there is the greatest economy of space and the most advantageous arrangement of apparatus.

At present two calorimeters are completed, one under construction, and two others are planned. The proposed calorimeters are to be placed in the spaces inclosed by dotted lines. Of the calorimeters that are completed, the so-called chair calorimeter, which was the first built, is in the middle of the west side of the room, and immediately to the north of it is the bed calorimeter, already tested and in actual use. On the east side of the room it is intended to place large calorimeters, one for continuous experiments extending over several days and the other large enough to take in several individuals at once and to have installed apparatus and working machinery requiring larger space than that furnished by any of the other calorimeters. Near the chair calorimeter a special calorimeter with treadmill is shortly to be built.

The heat insulation of the room is shown by the double windows and the heavy construction of the doors other than the double doors. On entering the room, the two calorimeters are on the left, and, as arranged at present, both calorimeters are controlled from the one platform, on which, is placed the observer's table, with electrical connections and the Wheatstone bridges for temperature measurements; above and behind the observer's table are the galvanometer and its hood. At the left of the observer's platform is a platform scale supporting the water-meter, with plug valve and handle conveniently placed for emptying the meter. The absorption system is placed on a special table conveniently situated with regard to the balance for weighing the absorbers. The large balance used for weighing the oxygen cylinders is directly across the center aisle and the analytical balance for weighing the U-tubes for residual analysis is near by.

Another view of the laboratory, taken near the door leading to the refrigeration room, is shown in fig. 3. At the right is seen the balance used for weighing absorbers, and back of it, imperfectly shown, is the case surrounding the balance for weighing oxygen cylinders. On the wall, in the rear, is the recording apparatus for electric resistance thermometers in the water-circuit, a detail of which is shown in fig. 23. In the foreground in the center is seen the observer's table; at the right of this is shown the table for the absorption system, and at the left the chair calorimeter with the balance for weighing subjects above it. The mercury-vapor light, which is used to illuminate the room, is immediately above the balance for weighing absorbers.

The bed calorimeter and the absorbing-system table are better shown in fig. 4, a general view of the laboratory taken near the temperature recorder. In the immediate foreground is the table for the absorption system, and back of it are the observer's table and chair calorimeter. At the right, the bed calorimeter with the front removed and the rubber hose connections as carried from the absorber table to the bed calorimeter are shown. At the extreme left is the balance for weighing the absorbers. Above the chair calorimeter can be seen the balance for weighing the subject, and at its right the galvanometer suspended from the ceiling.

The west side of the laboratory at the moment of writing contains the larger proportion of the apparatus. On the east side there exist only the balance for weighing oxygen cylinders and an unfinished[4] large calorimeter, which will be used for experiments of long duration. A view taken near the front end of the bed calorimeter is shown in fig. 5. At the right, the structural skeleton of the large calorimeter is clearly shown. Some of the copper sections to be used in constructing the lining of the calorimeter can be seen against the wall in the rear.

At the left the balance for weighing the oxygen cylinders is shown with its counterpoise. A reserve oxygen cylinder is standing immediately in front of it. A large calorimeter modeled somewhat after the plan of Sonden and Tigerstedt's apparatus in Stockholm and Helsingfors is planned to be built immediately back of the balance for weighing oxygen cylinders.

HEATING AND VENTILATING.

Of special interest in connection with this calorimeter laboratory are the plans for maintaining constant temperature and humidity (fig. 6). The room is heated by five steam radiators (each with about 47 square feet of radiating surface) placed about the outer wall, which are controlled by two pendant thermostats. A certain amount of indirect ventilation is provided, as indicated by the arrows on the inner wall. The room is cooled and the humidity regulated by a system of refrigeration installed in an adjoining room. This apparatus is of particular interest and will be described in detail.