Volume 2

An elementary system of physiology ... / [John Bostock].

  • John Bostock
Date:
1836
Catalogue details

Licence: Public Domain Mark

Credit: An elementary system of physiology ... / [John Bostock]. Source: Wellcome Collection.

    59/920 page 29
    stances, it consists essentially of oxygen, hydrogen, carbon, and azote. It has been observed that membrane is less disposed to. undergo the putrefactive fermentation than any of the soft parts of the animal body, a circumstance which may probably depend upon its containing but a very small proportion of either blood or fat, substances which are peculiarly disposed to spontaneous decomposition. The more dense varieties of membrane contain less water than many other of the solids of the body, and this may be one reason why they are less disposed to putrefy ; as we invariably find that moisture favours decomposition. By the assistance of heat membranous matter is soluble in the mineral acids ; its combination with the sulphuric and mu- riatic acids is not attended with any peculiarly interesting phe- nomena, but the effects which are produced by the nitric are more remarkable ; the membrane is partly dissolved and partly decomposed, and several new compounds are produced, which will be more fully described when I treat expressly upon the analysis of animal substances. Membrane is also soluble in the pure fixed alkalies, and a saponaceous fluid is formed, which has been employed, in some instances, instead of the coarser kinds of soap, made in the usual process, by the combination of alkali and oil. Membrane has a strong affinity for the tannic acid ; by uniting with a portion of it a dense, flexible, elastic compound is formed, little susceptible of putrefaction, which constitutes the basis of leather. The jelly, which enters so largely into the composition of some kinds of membrane, has also a strong attraction for the tannic acid, and forms with it a substance, which appears in its chemical properties to resemble that produced by tan and the proper basis of membrane, the albumen. But it necessarily differs in its mechanical consistence, as the jelly, at least in the ~ form in which it is usually employed, is dissolved in water, and of course without any regular organization of its particles, or even any adhesion between them. ‘The mineral acids and the pure alkalies, when assisted by heat, readily dissolve jelly, but nothing very interesting or important results from their com- bination ; the compound of jelly and alkali does not appear to possess that saponaceous property which exists in the com- pound of albumen and alkali °. It appears from the analysis of MM. Gay-Lussac and Thenard, and of Dr. Prout’, that jelly, as well as albumen, contains less 1 Phil. Trans. for 1800, p. 379; Turner’s Chem. p-. 936. .0. - 2 Children’s Thenard, p. 357; Thenard, Traité de Chimie, iv. 204. The following are the results of Thenard’s analysis : Carbon. Oxygen. Hydrogen. Azote. EADTM Utes dhle is es ss se DS -O6D os 00 ee 19869 0, 01d POD. a vinie’s 19.934 - AUB UME. 6:5 6.5 asic 96 06 52. BBR iais ss BT eh oe c TOAO. » sas 15.705 Nes xthenosa bei izessi eo o-0i 586 47. BS) ce oie’ DE BOT snsvee s Lia sve 16.988 Albumen(by Dr. Prout)50. —....-- 26.67 ..+-- PY Te Meee 15,55 It will be seen, that the analysis of albumen, as given by Dr. Prout, differs
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