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""The physics of heat and vaporization: its history and application to the design of anaesthetic vaporizers.""

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(1999)CPD Anaesthesia 1 (1999): 88-93

PDF posted with permission of the author.

From the Introduction:

"Contrary to what appears to be the general impression, the first ether anaesthetics were administered using apparatuses, or vaporizers, not by the more primitive 'open" or 'rag and bottle' method which soon displaced them. All these early inhalers were based on apparatus, general chemical, already in existence. . . . Everyone was in a hurry, and designed his own, so they were one-offs, made by the local instrument maker, and of material that a craftsman could readily adapt, which meant glass. The limitations of these early vaporizers are apparent in the number of contemporary accounts of failure to anaesthetise patients adequately or not at all. Those whose experience extends to before the 1950s will be well acquainted with the difficulty of achieving an adequate depth of anaesthesia when ether was being vaporized in the glass bottle of a Boyle's machine. They would have observed the condensation of water vapour from the air onto the surface of the bottle, and even ice formation. They would have attempted to raise the ether concentration by the application of warmth, either from the hand, or the warm water can which hooked on to the back bar. So here already we see some of the important physical principles which influenced the design of vaporizers. These were first put into effect by John Snow, who, by the end of January 1847, had designed a metal vaporizer which allowed him, by controlling the ambient temperature, to determine the ether concentration" (88).

Dalton's "New Table of Temperature" (1808) on page 90 is reproduced below in the event that it's blurry in the PDF when downloaded. Please click this thumbnail for a magnified image.


Fig. 3 is reproduced in the thumbnail below:


The original was published on p. 501 in part 1 of Snow's article, "On the inhalation of the vapour of ether" (19 March 1847).

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