A HISTORY OF SCIENCE 



phurous acid, had been utilized on a commercial scale 

 for refrigerating purposes. To-day every brewery and 

 every large cold-storage warehouse is supplied with 

 such a refrigerator plant, the temperature being thus 

 regulated as is not otherwise practicable. Many large 

 halls are cooled in a similar manner, and thus made 

 comfortable in the summer. Ships carrying perish- 

 ables have the safety of their cargoes insured by a re- 

 frigerator plant. In all large cities there are ice manu- 

 factories using the same method, and of late even 

 relatively small establishments, hotels, and apart- 

 ment houses have their ice-machine. It seems prob- 

 able that before long all such buildings and many 

 private dwellings will be provided with a cooling ap- 

 paratus as regularly as they are now equipped with a 

 heating apparatus. 



The exact details of the various refrigerator machines 

 of course vary, but all of them utilize the principles that 

 the laboratory workers first established. Indeed, the 

 entire refrigerator industry, now assuming significant 

 proportions, may be said to be a direct outgrowth of 

 that technical work which Davy and Faraday inaugu- 

 rated and prosecuted at the Royal Institution a re- 

 sult which would have been most gratifying to the 

 founder of the institution could he have forecast it. 

 The usual means of distributing the cooling fluids in 

 the commercial plants is by the familiar iron pipes, 

 not dissimilar in appearance (when not in operation) 

 to the familiar gas, water, and steam pipes. When 

 operating, however, the pipes themselves are soon 

 hidden from view by the thick coating of frost which 

 forms over them. In a moist beer-cellar this coating 



62 



