Harold M. Sylvester and William J. Houlihan
Trubeck Laboratories East Rutherford, N e w Jersey
I
I
A Refractometer Cooling System
An inexpensive, conveniently assembled water cooling system for a laboratory refractometer is shown in the accompanying diagram. The cooling capacity of this system is developed by the controlled rapid evaporation of a low-boiling organic liquid. The equipment needed for this unit is a jacketed spiral condenser ( A ) , a water trap with a one way stopcock ( B ) , a pinch or screw clamp ( C ) , a medicine dropper (D), and several lengths of water and pressure tubing. The lower arm (E) of the condenser is fitted with a short length of tubing to which is attached a dropper (D) and the clamp (C). The upper arm ( F ) is connected to the water trap ( B ) which in turn leads to a water aspirator. The spiral's top end ( G ) is connected to a water inlet, while the bottom (H) is joined to the water inlet of the refractometer. I n operating conditions the condenser jacket (I)is filled to about onehalf volume with methanol, benzene or benzenetoluene by siphoning the liquid through the dropper (D). It is recommended that the jacket should not be filled more than two-thirds of its volume since foaming a t the start of aspiration will cause mechanical losses. I n operation, the water aspirator is turned on so that the organic liquid does not foam or bump excessively. The water is passed slowly through the refractometer until the desired operating temperature is obtained. At this point the aspirator and water inlet are balanced to insure a constant temperature.
538
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Journol of Chemical Education
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TO WATER INLET
