78 



THE WORLD'S ADVANCE 



An Oxygen Generator 



Oxygen generators are indispensable 

 to the chemical laboratory. They can be 

 made in a variety of forms, one of the 

 simplest yet most reliable of which is 



shown in the accompanying drawing. Its 

 action is based on the fact that when a 

 three-to-one mixture of chlorate of pot- 

 ash and black oxide of manganese is 

 heated, free oxygen is given off. The 

 chemicals should be heated very slightly. 

 The best way to accomplish this is to 

 rest the bottle in a tin cup partly filled 

 with silver sand under which the flame 

 is placed. A glass tube should lead from 

 a rubber cork in the generator bottle into 

 a wash bottle filled with water. The gas 

 is thoroughly cleaned here and flows 

 through a glass tube which terminates in 

 a water vessel, where the gas is collected 

 in bottles, as indicated. The corks should 

 be sealed with shellac to prevent leak- 

 age. 



Contributed by 



H. A. MclLVAINE. 



Makeshift Ruby Lamp For Traveling 

 Photographers 



An emergency ruby lamp for the ama- 

 teur photographer whose developing kit 

 lacks a standard dark lamp can be made 

 by tying a piece of red paper over the 

 bulb of a pocket flash light. Extreme 

 care should be taken in selecting the 

 paper which is to be used. A better 

 plan, probably, than the foregoing is to 

 carry a small ruby bulb which can be 

 substituted for the regular bulb of the 

 flash lamp. 



Contributed by T. N. SLOCUM. 



Chewing Gum a Puncture Remedy 



In an emergency a puncture in a bi- 

 cycle tire can be repaired by chewing 

 gum forced into the hole and held in 

 place by a handkerchief bound tightly 

 around the tire. 



Contributed by 



DONALD OLSON, JR. 



Pulls Whistle Electrically 



In water power or electric lighting 

 plants in small towns, where expense 

 prohibits the installation of the usual 

 electric fire whistle, an attachment can 

 be fitted to the plant whistle, which will 

 serve the purpose practically as well as 

 the costlier made-to-order installation. 



A heavy board should be nailed to 

 some support below the whistle. A long 

 metal beam, weighted at one end and 

 pivoted at the other to a small pedestal, 

 should be attached by a wire or stout 

 cord to the whistle valve. A pair of 

 electromagnets should be mounted on the 

 board, and a pivoted release bar placed 

 below them so that a broad flare at the 

 upper end of the bar will come within a 

 fraction of an inch of the cores. The 

 flare acts as an armature. When current 

 is sent through the coils of the magnets 



We/ghf 



the armature is drawn down, a catch at 

 its lower end releases the weighted beam, 

 and the whistle blows until the beam is 

 put back in place. 



A small block of wood should be 

 nailed at the lower corner of the board 

 to act as a stop. 



Contributed by FRANK SAHLMAN. 



