The properties and uses of pure glycerin / by M.D., M.R.C.S.

Date:
[1898?]
Catalogue details

Licence: Public Domain Mark

Credit: The properties and uses of pure glycerin / by M.D., M.R.C.S. Source: Wellcome Collection.

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    molecular change in the nerve endings, v/hich subserve these functions. This property bears some relation to the specific gravity or vapour density of the body which produces the smell or taste. Prussic acid, HCN, with a vapour density of 7*5, is, I believe, the lightest body known which we can smell. This is especially extraordinary, as prussic acid is also one of the most violent poisons known. This almost exceptional property it possesses—exceptional, I mean, in regard to its vapour density— seems a most useful arrangement on the part of Nature, because, as the substance is so violent a poison, it is most important that it should possess the property of smell. Although our smell and taste organs are tuned, so to speak, like our ears, to a certain pitch, i.e.y only to smell or taste substances within a certain range of specific gravity or vapour density, the noses and palates of animals are, in certain cases, much more sensitive; that is, act through a much greater range of substances. To return to our subject, from which, I am afraid, we have digressed, the sweetish taste of Glycerin, from a pharmaceutical standpoint, greatly increases the sphere of its usefulness. Many substances are rendered palatable—that is, their own nasty taste is neutralized— by the addition of a little Glycerin. It would be out of place to discuss further here what the property of taste possessed by Glycerin depends upon. In this connection it may however be mentioned, that Glycerin possesses to a remarkable degree the property of attracting water. When a drop of it falls or finds itself upon a mucous membrane possessed of taste goblets, it is probable that the marked difference in the osmotic tension between the drop of Glycerin and the fluid in the taste goblet causes a flow of water from the latter to the former in an attempt to establish osmotic equilibrium. This is a physical stimulation, and would throw into vibration the receiving molecule of the taste goblet. This molecular disturbance in the taste goblet becomes known to us as taste, or, rather, as the taste of the Glycerin. The resemblance between Glycerin and sugar will be con- sidered more fully elsewhere; it may, however, be mentioned here that they are both strong dehydrating agents, i.e., have the power of drawing water out of water-containing substances, and that they both taste sweet. In short, when a drop of syrup or Glycerin is placed upon the mucous membrane of the tongue, they would