On disinfection by heat : with a description of a new disinfecting chamber / by James Adams, M.D.

  • Adams, James Maxwell, 1818-1899.
Date:
1883
Catalogue details

Licence: Public Domain Mark

Credit: On disinfection by heat : with a description of a new disinfecting chamber / by James Adams, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    With the colder infected objects instantly condenses upon them Until all are damped and moist, and wlien tlie pressure is removed the loater, no longer restrained, eva])orates, and the objects remain in an almost dry condition:' M. Vallin, when comment- ing on this phenomena, says this is what we do not very well understand, and his difficulty claims sympathy. An eye-witness to the process whose evidence is adduced by the maker says on opening the door the several articles above named {i.e., various fabrics and a letter in coloured ink] were to our surprise and satisfaction perfectly dry^ / Now there is here a blowing of hot and of cold, a condensing, a wetting, and a damping con- joined with a provision against condensing, or wetting that needs to be reconciled. My explanation is that the maker's theory—a very pretty one by the way—is altogether based on a fallacy. I feel assured that no condensation of steam can take place unless slight and momentarily at the close of the process when the articles are being removed from the chamber. At the instant when the cover is swung aside there will take place a rush of cold air, a portion of steam will be condensed, and the remainder dissipated. For steam so far from being a moist fluid is perfectly dry as long as it retains the elastic force due to its temperature—that is, so long as the temperatm-e does not fall; and in this case the temperature is kept up by the hot outer casing and the continuous supply of hot steam, from be- ginning till the end of the process. It has been pointed out by a great authority that steam is of so drying a nature that it cannot be contained in wooden vessels (however well seasoned they may be) without di'ying them and making them shrink till they crack and fall to pieces. Steam is never moist. When steam is condensed it becomes water itself, and the mere removal of pressure will not evaporate water, although it will permit the dispersion of steam wnen liberated from pressure. If the articles placed in the disinfector under consideration are ever penetrated with steam that has condensed, then assuredly they are wetted with water as effectively as if cold water had been poured upon them, and that water will only evaporate under a separate drying operation. If the chamber had been filled only with satm'ated steam, and if that steam had been isolated from water in a space of fixed dimension, and if the temperature had been permitted to fall, instead of being steadily maintained, there would then have been a certain amount of condensation, although very trivial because of the little margin of fall that could be possible under the conditions. But the chamber is not filled with satu- rated steam, but with a mixture of hot air that previously filled the chamber, conjoined with as much moisture from the steam as the air can absorb, viz., about five-eighths of the gross weight