THK RESPIRATION APPARATUS. 13 



of the furniture and fixtures is given, while figure 33, on page 124, gives 

 a clearer presentation of the interior appearance. 



The ceiling, floor, and walls of the chamber, with the exception of 

 the window and the various other small openings to be described, are 

 constructed of sheet copper. The use of metal is especially advanta- 

 geous in securing an airtight chamber. A so-called " i4-ounce " sheet 

 copper (Brown & Sharpe gage No. 24), cold-rolled, was selected, extra 

 large sheets being specially obtained to reduce the number of seams to 

 a minimum. For the floor of the chamber two of the sheets were 

 soldered together in such a manner that one seam runs lengthwise of 

 the chamber, and were then cut to the area and form of the chamber 

 (the corners being rounded, as shown in several of the figures given). 

 The ceiling is a duplicate of the floor. For the sides and ends of the 

 chamber, five of the sheets were soldered together side to side, and bent 

 to conform with the ceiling and floor, which were then soldered to the 

 upper and lower edges. 



The copper chamber thus constructed is fastened to a wooden frame- 

 work or skeleton by means of strips of copper soldered to the outside of 

 the chamber. Beneath the copper floor the framework is made solid 

 practically a wooden floor to prevent the denting and puncturing of the 

 copper when stepped upon. 



The respiration chamber also serves as a calorimeter chamber and is 

 fitted with many devices for the maintenance of constant temperature. 

 For this purpose the chamber just described is surrounded by a similar 

 chamber of zinc and an outer casing of wood. Detailed description of 

 these features is deferred to that portion of the report dealing with the 

 calorimetric apparatus. 



OPENINGS IN THE CHAMBER. 



While the copper wall of the chamber is carefully soldered at all 

 joints, and therefore perfectly airtight, it contains, as has been indi- 

 cated, a number of special openings. Certain precautions are neces- 

 sary at these points to guard against leakage of air into or out of the 

 system. 



Window. The largest opening is that which serves both as door and 

 window, shown at the front end of the chamber in figures 3 and 8. It 

 is 49 cm. wide and 70 cm. high, being of sufficient size to allow a man 

 to enter comfortably and to introduce and remove the various pieces of 

 apparatus. A strip of metal which forms a small shoulder or beading 

 on the inside of the window frame is securely soldered on all four sides. 

 The opening itself is finally closed by a piece of plate glass which rests 



