894 



Popular Science Monthly 



As in other machines, the motor is 

 started and stopped by means of a 



This machine has a rotary compressor and 



employs ethyl chloride as a circulating 



refrigerant 



thermostat in the refrigerator. The 

 weight of this machine complete, in- 

 cluding the brine tank, is about i6o 

 pounds. 



In recent years much has been done 

 towards the development of an absorp- 

 tion household -machine, and several 

 meritorious machines of this type are 

 now on the market. An absorption 

 machine is much like the compression 

 machine, the principal difference being 

 that the compressor is replaced by a still 

 or boiler. This still is partially filled 

 with strong aqua ammonia. When 

 heat is applied to the still the dissolved 

 ammonia is driven off as a gas into 

 the condenser, where it is converted into 

 liquid ammonia just as in the compres- 

 sion machine. After all the ammonia 

 is driven off from the still and collected 

 in the condenser, the burner under the 

 still is extinguished and the still, with 

 the water from the aqua ammonia, is 

 allowed to cool down. Cold water 

 has a great affinity for ammonia and at 

 once begins to take up gas from the liquid 

 ammonia which flows from the con- 



denser into the refriger- 

 ating-coils. This evapo- 

 ration of liquid ammonia 

 in the refrigerator coils 

 causes intense cooling.' 

 Check valves are placed 

 between the still and 

 condenser and between 

 the refrigerator-coil and 

 still so as to make the 

 ammonia flow in the 

 proper direction. Of course there is no 

 cooling done during the distillation 

 period, but this period is generally very 

 short compared with the absorption 

 period. -Usually one distillation a day is 

 sufficient. One great advantage of this is 

 that there are no moving parts and hence 

 no noise. The flow of the fuel gas and 

 cooling water is automatically controlled 

 in the later machines. The automatic 

 devices will need some attention to keep 

 them in order, especially the check- 

 valves. The principal objection to these 

 absorption machines is the high tempera- 

 tures and pressures used. The alternate 

 heating and cooling of the still tends to 



' ' B a rsm i t h 

 liquid," which 

 is similar to 

 sulphur-dioxide, 

 is the refrigerant 

 used in this com- 

 pact machine 



