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

by Francis Gano Benedict and Thorne M. Carpenter.

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 a.s.sociates: 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 a.s.sociated 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, Ma.s.sACHUSETTS, _August 10, 1909._

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. At.w.a.ter. Appreciating the remarkable results of Pettenkofer and Voit[1] and their a.s.sociates, 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 bas.e.m.e.nt of a chemical laboratory. With four sciences crowded into one building it was practically impossible to devote more s.p.a.ce 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 acc.u.mulated, 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 Inst.i.tution of Washington for 1908, is of plain brick construction, trimmed with Bedford limestone. It consists of three stories and bas.e.m.e.nt and practically all the s.p.a.ce 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] At.w.a.ter, 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. At.w.a.ter and F. G. Benedict: A respiration calorimeter with appliances for the direct determination of oxygen. Carnegie Inst.i.tution 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 gla.s.s 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 s.p.a.ce 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 s.p.a.ce 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 s.p.a.ces 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 s.p.a.ce 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 a.n.a.lytical balance for weighing the U-tubes for residual a.n.a.lysis is near by.

[Ill.u.s.tration: FIG. 1.--General plan of respiration calorimeter laboratory.]

[Ill.u.s.tration: FIG. 2

General view of laboratory room taken near the main door. At the extreme right is the absorber table, and back of it the bed calorimeter. In the immediate foreground is shown the balance for weighing absorbers. A sulphuric acid absorber is suspended on the left hand arm of the balance. At the left is the observer's table and back of it the chair calorimeter with a large balance above for weighing subjects. On the floor, to the left, is the water meter for weighing water used to bring away heat.]

[Ill.u.s.tration: FIG. 3

General view of laboratory taken near the refrigeration room. The observer's table is in the immediate foreground with water balance at the left, and chair calorimeter with balance for weighing man at the extreme left. At the right of the observer's table is the absorption system table, and on the wall in the rear the temperature recorder. At the right is shown the balance for weighing absorbers, and back of that the case surrounding the balance for weighing oxygen.]

[Ill.u.s.tration: FIG. 4

General view of laboratory taken near the temperature recorder. The bed calorimeter is at the right, the absorber table in the immediate foreground, back of it the chair calorimeter and observer's table, and at the left the balance for weighing absorbers. Near the ceiling are shown the ducts for the cold air used for temperature control.]

[Ill.u.s.tration: FIG. 5

View of laboratory taken from the entrance of the bed calorimeter, with balance for weighing oxygen cylinders at the left. The structural steel skeleton of the calorimeter for long experiments is at the right and sections of the copper lining are in the rear, resting against the wall.]

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.

[Ill.u.s.tration: FIG. 6.--Plan of heating and ventilating calorimeter laboratory, showing general plan of circulation of the special cooling system and the position of the thermostats and radiators which they control. The two small diagrams are cross-sections of brine and heating coils.]

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.