THE BROWN-DUVEL, MOISTURE TESTER 
13 
inch in diameter, with 20 wires to the inch and with a 2-inch as- 
bestos center, as shown in Figure 12. 
The asbestos center insures a uniform distribution of heat and adds 
greatly to the life of the wire. It can readily be put in by mixing 
asbestos cement with water and rubbing it into the mesh of the gauze. 
The asbestos center should always be kept in good condition in order 
to prevent the flame from playing directly on the bottom of the flask. 
Fiu. 12. — Wire gauze, with asbestos center 
CONDENSER TUBES 
The glass condenser tubes are 34 centimeters in total length, 0.70 
centimeter in diameter, and the upper 3 centimeters flanged to an 
inside diameter of 2.1 centimeters so that it just fits a No. 3 stopper. 
The tubes should be so adjusted in the No. 5 rubber stoppers that, 
when the latter are firmly pressed into the holes in the bottom of 
the cold-water tank, the tops of the tubes will be approximately one- 
fourth inch above the top of the tank. 
RUBBER STOPPERS 
The No. 5 one-hole rubber stoppers which carry the thermometers 
and the No. 3 one-hole rubber stoppers used on the side tubes of the 
flasks should be of such quality as will withstand comparatively 
