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Engraving 3 in Snow's 1847 book showing a mouth piece for the application of ether. The dotted lines indicate the position of the expiratory value when turned aside for the admission of unvaporized air. |
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Engraving 3 in Snow's 1847 book showing a mouth piece for the application of ether. The dotted lines indicate the position of the expiratory value when turned aside for the admission of unvaporized air. |