324 THE SCIENTIFIC PAPERS OF 



recoiidensation was added to the compressed steam and served to 

 make up for losses by radiation, &c. It was evident that by such 

 an arrangement the latent heat of the same steam could be used, 

 not once or twice, but several times, the heat passing again and 

 again through the same metallic surfaces. "Whether such a plan 

 could be worked advantageously in practice in the East and West 

 India sugar factories was a question upon which Mr. G. W. Siemens 

 had no experience to adduce, but the experiments had at any rate 

 proved the correctness of the principle involved. 



In the discussion of the Paper 



" ON THE MECHANICAL PRODUCTION OF COLD," 

 By ALEXANDER CARNEGIE KIRK, Assoc. Inst. C.E., 



MR. SIEMENS * said if he wished to be critical he might find 

 fault with the title of the paper. The author spoke of a machine 

 for " the production of cold." Cold was the absence of heat, and 

 it might be open to question whether it was possible to produce 

 the absence of a thing. Eefrigeration, which he thought the 

 preferable word, meant the transfer of heat from one substance to 

 another of the same or a superior degree of temperature, and the 

 author evidently agreed in that definition. The subject was one 

 of considerable interest at the present time. Refrigerating 

 machines were now largely used in breweries, since fermentation 

 went on to advantage only at a temperature a little above freezing 

 point ; and to attain that point during all seasons of the year 

 rendered artificial means of maintaining a low temperature 

 necessary, unless native ice was employed for the purpose. For 

 preserving meat also in hot climates and transporting it, artificial 

 means of reducing the temperature were coming into use, and 

 would be more extensively employed if a cheap and ready method 

 could be devised. Refrigeration was of great importance in hot 



* Excerpt Minutes of Proceedings of the Institution of Civil Engineers, Vol. 

 XXXVII. Session 1873-74, pp. 283-287, 300-301. 



