Supplement to Minutes of the course of chemical instruction in the Medical Department of the University of Pennsylvania / by Robert Hare, printed for the use of his pupils.

  • Hare, Robert, 1781-1858.
Date:
1824
Catalogue details

Licence: Public Domain Mark

Credit: Supplement to Minutes of the course of chemical instruction in the Medical Department of the University of Pennsylvania / by Robert Hare, printed for the use of his pupils. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    Gluten is distinguished, by approaching more to the na- ture of animal matter, than other products of vegetation.— Like animal substances, it yields ammonia by distillation— and of course contains nitrogen. It is to the presence of Glu- ten in wheat flour, that its pre-eminence in nutritive power is ascribed, by Europeans. By trituration, with alcohol, it is susceptible of forming a kind of varnish. To the glutinous property of this substance, dough is sup- posed to owe its rising, during the process of panification, after being mixed with leaven or yeast. The cellular part of leavened bread, is indebted, for its ex- istence, to Gluten, which, by confining the gaseous matter arising from an incipient fermentation, is inflated into innu- merable cavities. Farinaceous matter, destitute of Gluten, can only be made into heavy cakes, as are those of Indian meal. One of the principal defects of bread, is sourness, arising from acidity in the yeast. This may be easily removed, by pearlash, or a filtered infusion of clean ashes. It is alleged by M. Taddei, an Italian chemist, that Gluten, when subjected to alcohol, is separated into two principles— one, soluble in that fluid, which he calls Gliadine—the other, insoluble, which he calls Zimome. Of the presence of Zi- mome, gum guaiacum is said to be a test—producing, with flour, in which it exists, a fine blue colour—whereas, with starch, or bad flour, guaiacum does not cause this colour. OF CAOUTCHOUC. Caoutchouc, or Elastic Gum, is a very singular substance— not only from its extraordinary mechanical properties, but from its insolubility, both in water and alcohol, and remaining untouched even by acids, unless aided by heat. Ether, and the volatile oils, dissolve it slowly. The oil of cajuput, is said to be its best solvent. Turpentine, repeatedly rectified, dissolves it, and forms, with it, an elastic varnish. Caoutchouc burns with a bright flame, especially in oxygen gas. It exudes, in the fluid state, from certain plants, and