Page:Popular Science Monthly Volume 39.djvu/29

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ICE-MAKING AND MACHINE REFRIGERATION.

St. Bernard still complained that monks had too much to do with medicine; and a few years later we have decretals like those of Pope Alexander III forbidding monks to study or practice it. In the beginning of the next century Innocent III, in the Council of the Lateran, forbade surgical operations to be practiced by priests, deacons, and sub-deacons; some years later Honorius III reiterated this decree and extended it. In 1243 the Dominican Order forbade medical treatises to be brought into their monasteries. Five years later the Council of Le Mans forbade surgery to monks, on the ground that "the Church abhors the shedding of blood," and many other councils did the same. At the end of that century Boniface VIII interdicted dissections as sacrilege.[1]


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ICE-MAKING AND MACHINE REFRIGERATION.

By FREDERIK A. FERNALD.

THE manufacture of ice now bids fair to become a regular industry in temperate as well as in tropical climates. Pioneer work in this field was done more than sixty years ago, but it is only within the last ten years that the groping attempts of the early inventors have developed into processes sufficiently economical to make the artificial production of ice a commercial success. Artificial ice has been made in tropical countries and in our Southern cities for many years, but the industry has been greatly extended in this country by the two successive mild winters of 1888-'89 and 1889-'90. It has now gained a foothold even in our Northern States, while in the South comparatively small towns have their ice factories.

The scientific fact on which the making of artificial ice depends is that when a liquid evaporates it uses up a great deal of heat, which it draws from anything that happens to be around it. If a can of water is at hand, its temperature is reduced, and if the action goes far enough the water will be frozen. This cooling action can be felt by pouring a little ether or alcohol upon the hand. The liquid evaporates rapidly, and the loss of the heat which it takes up cools the hand very perceptibly. If a bottle

  1. For exact statements as to these decrees of the highest Church and monastic authorities against medicine and surgery, see Sprengel, Baas, Geschichte der Medicin, p. 204, and elsewhere; also, Buckle, Posthumous Works, vol. ii, p. 567. For a long list of Church dignitaries who practiced a semi-theological medicine in the middle ages, see Baas, pp. 204, 205. For Bertrarius, Hildegarde, and others mentioned, see also Sprengel and other historians of medicine. For clandestine study and practice of medicine by sundry ecclesiastics in spite of the prohibitions by the Church, see Von Raumer, Hohenstaufen, vol. vi, p. 438.