914 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Professor Gutbrie lias not succeeded in getting tlie cryoliydrates of 

 glycerine. As a cryogen, the glycerine behaves as liydrocliloric acid 

 and other liquid elements of crj'ogens, namely, the temx^eratin-e obtained 

 is lower if the liquid be previously cooled. 



K.— ceyogex-machi]s:es. 



Under this name may be included any apparatus calculated to faciUtate 

 and bring about the regular admixture of water and a cryogen, the low 

 temperature produced being utilized to make ice, freeze creams, &c. The 

 only practical domestic machines are really of this kind, and to what ex- 

 tent they ]nay hereafter render good service in households and some indus- 

 tries, especially in hot climates, depends much on the careful ai^plication 

 of the knowledge acquired by Professor Guthrie and his followers. Many 

 of the salts available for this purpose are remarkable for their stability, 

 and may be used for an indefinite period of time. The cost of the evap- 

 oration of water will determine the cost of the resulting cold, and the 

 sun's heat may enable, the parched residents of tropical countries, to 

 enjoy the comfort and luxmy of very economical methods of artificial 

 refrigeration. 



In relation to fish-culture, the transportation of ova on steamers, and 

 for seciu-ing definite and unvarying temperatiu'es at small cost, in mod- 

 erate compass, the cryogen-maclime otters many advantages. At sea, 

 exhaust steam may be had in any quantity to dry the salt. The time 

 required to dry the salt, the amount of material to be cooled, and the 

 mechanical facilities for the alternate liquefaction and solidification of 

 the salt are matters of great i^ractical moment which have received but 

 little attention hitherto. In this direction we must anticipate a great 

 revolution in artificial refrigeration, especially as ajiplied to the subjects 

 most immediately under consideration in this i)aper. I need, therefore, 

 make no excuse for reproducing the following table, showing (1) the 

 chemical formula of the salt, (2) the lowest temperature to be got by 

 mixing the salt with ice, (3) temperature of solidification of the cryohy- 

 drate, (4) molecular ratio between anhydrous salt and water of its cryo- 

 hydrate (water-worth or aquavalent), (5) percentage of anhydrous salt 

 in portions of cryohydi'ate last to solidify, (G) percentage of anhydrous 

 salt in croi) of cryohydrate before the last. 



