CALORIFIC POWER OF FUELS. 



platinum cap ; the end s is soldered to a copper tube, sy, pass- 

 ing into a Liebig condenser having two tubes, oo' , for the 

 water. In most cases the platinum tube may be replaced 

 without trouble by one of copper, or even iron, the platinum 

 being necessary only when the gases are drawn at a tempera- 

 perature high enough to cause oxidation of the other metals. 

 With iron or copper a portion of the oxygen is removed in 

 the passage through the tube. 



The tube ry is open at y, and has a side tube h. Aspira- 

 tion is carried on through the opening in the platinum tube. 

 A movable rod, ik, carrying a platinum scraper is attached 

 to one end of the tube, and moves in the slot to clean it, as 

 occasion requires, from soot, etc. The disk/> serves to hold the 

 cement used in fastening it to the stack or chimney, and pre- 

 vents ingress of external air. The rod mn passes through a 

 caoutchouc bearing fastened between the disks/ and q. 



Fig. 28 represents a front view of the apparatus. Fig. 30 

 represents a side view in elevation. The tube ry is intro- 

 duced through an opening made for the purpose in the 

 masonry, the pait rs being exposed inside. The end y, is 

 connected with a lead pipe, v, by a rubber tube ; this pipe is 

 soldered to another one, yz. On opening the cock y, water 

 flows from a reservoir and empties at 2. Suction in yrs 

 should amount to several millimetres of mercury, and is regu- 

 lated by the cocksy and x controlling the water-flow, and also 

 by the length of yz. The gas drawn in by yvx may be meas- 

 ured by collecting it at z, and should amount to 4 or 5 litres 

 (25 to 30 cubic inches) per minute. 



The gas-holder is supported by a piece of sheet iron with 

 upturned edges forming a shelf. Any mercury spattered 

 over or spilled is thus easily collected. The mercury tank is 

 supported from the wall of the chimney in such position as to 

 facilitate refilling the flask through a siphon. The tubes dd f 

 serve to feed the condenser. 



While the current is passing through yr a small quantity 



