Page:Popular Science Monthly Volume 92.djvu/585

 rop/iliir Science Montlilij

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��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-

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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.

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