rop/iliir Science Montlilij 



509 



This Regulator Will Keep Your Ap- 

 paratus at a Constant Temperature 



IN fractional dis- 

 tillation and 

 other chemical 

 operations it is 

 often necessary to 

 keep the material 

 which is being used 

 at a constant tem- 

 perature for many 

 hours, or even 

 days. This is par- 

 ticularly difficult 

 when electricity is 

 used as the source 

 of heat. 



Mr. Louis Ve- 

 laseo, of Wilming- 

 ton, Del., has 

 invented an im- 

 provement for au- 

 tomatic thermal 

 cutouts for electric 

 circuits which is 

 adapted for use in 

 connection with 

 heating apparatus. 

 After the heat has 

 reached a prede- 

 termined degree 

 the current is shut 

 off until the tem- 

 perature falls to a 



given point, when the current is again 

 switched on and the temperature again rises. 



A recepta- 

 cle containing 

 air, or other 

 gas, communi- 

 c a t e s b \' 

 means of a 

 small diameter 

 tube with a 

 glass U-tube 

 containing 

 oil, on the out- 

 side of the 

 evaporator. 

 As the temper- 

 ature rises, the 

 expansion of 

 the air in the 

 container 

 forces the oil 

 around the U- 



neat i ^ 



Chemical appara- 

 tus is kept at a con- 

 stant temperature 

 by this ingenious 

 thermostatic device 



The painter's equipment is carried in a neat box 

 behind driver's seat of this specially built buggy 



tube and raises a weight which rests on 

 the surface of the oil. This motion is 

 transmitted by a string to a pulley, to 

 which is afli.\ed a 

 contact-arm which 

 makes contact on 

 an arc-shaped piece 

 of metal. As the 

 temperature con- 

 tinues to rise the 

 arm is moved over 

 the metal plate un- 

 til at length it pass- 

 es beyond it and so 

 cuts off the current. 

 When the tempera- 

 ture falls again, the 

 gas in the container, 

 following Charles' 

 Law of Tempera- 

 tures, contracts and 

 the contact arm 

 creeps back over the plate until at last 

 contact is again made, the weight now 

 actuating the arm. The apparatus can be 

 adjusted to operate over a considerable 

 range and answers its purpose very well. 



Helping to Make Los Angeles a Spot- 

 lessly Clean Town 



ES ANGELES is on display to ex- 

 pectant tourists so many months of 



the year that she must always be dressed 



for company. 



One man is employed exclusively to 



paint the water hydrants. This single 



little item in 

 keeping the 

 city well 

 groomed re- 

 quires, besides 

 the services 

 of a painter, a 

 specially built 

 b u g g \- in 

 which the 

 necessary 

 equipment is 

 carried in a 

 neat box be- 

 hind the seat. 



It is carried 

 on under the 

 direction ot the 

 local fire de- 

 partment. 



