16 



CALORIMETERS FOR STUDYING RESPIRATORY EXCHANGE, ETC. 



seams for soldering, and seams are made tight only with difficulty. The cop- 

 per is of standard gage, the so-called 14-ounce copper, weighing 1.1 pounds 

 per square foot or 5.5 kilograms per square meter. It has a thickness of 0.5 

 millimeter. The whole interior of the skeleton frame of the structural steel 

 is lined with these sheets ; fig. 11 shows the copper shell in position. 



For the outer metallic wall, zinc, as the less expensive metal, is used. One 

 sheet of this material perforated with holes for the attachment of bolts and 

 other appliances is shown in position on the outside of the wall in fig. 11. 

 The sheet zinc of the floor is obviously put in position before the channels 

 upon which it rests are laid. The zinc is obtained in standard size, and 



FIG. 12. Cross-section in detail of walls of calorimeter, showing zinc and copper 

 walls and asbestos outside- (A) ; hair-felt lining (B) ; cross-section of channel iron 

 (H) ; brass washer soldered to copper (K) ; asbestos insulation between channel 

 iron and copper (J) ; bolt holding the whole together (I) ; heating wire (W) and 

 insulator holding it (F) shown in air-space between zinc and hair-felt; section of 

 one of the cooling pipea (C) and its brass support (G) ; threaded rod (E) fastened 

 into H at one end and passing through asbestos wall with a nut on the outside; 

 and iron pipe (W) used as spacer between asbestos and zinc. 



is the so-called 9-ounce zinc, or 0.7 pound to the square foot, or 3.5 kilo- 

 grams to the square meter. The sheet has a thickness of 0.5 millimeter. 

 In the cross-sectioD, fig. 7, A represents the copper wall and B the zinc 

 wall. Surrounding this zinc wall and providing air insulation is a series of 

 panels constructed of asbestos lumber, very fire-resisting, rigid, and light. 

 The asbestos lumber used for these outer panels is 6.4 millimeters (0.25 

 inch) thick. To further aid in heat insulation we have glued to the inner 

 face of the different panels a patented material composed of two layers of 

 sheathing-paper inclosing a half-inch of hair-felt. This material is com- 



