Observations on the changes produced in the blood &c / by Charles J.B. Williams.

Date:
[1835]
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Licence: Public Domain Mark

Credit: Observations on the changes produced in the blood &c / by Charles J.B. Williams. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    matter, as in the meshes of a net, and by its contraction separates them from the serum. [Berzelius and Dr. B. Babington have confirmed this view, by shewing that fibrine exists in the blood in a liquid state, and that the firmness and contraction of the coagulum are due to the attraction which the particles of fibrine, on becoming solid, exert towards each other.] It would appear from the experiments of Sir E. Home and Mr. Braude *, that carbonic acid gas is extricated from the blood in the act of coagulation. I am inclined to doubt that this occurs to any extent when the action of external air is excluded; for I have been unable to perceive any appreciable extrication of gas when blood is allowed to coagulate in a Torricellian tube inverted over mer- cury . [My doubts on this subject arc fur- ther warranted by the subsequent ex- periments of Dr. John Davy and Dr. Christison, who could not extricate any gas from blood during coagulation when the air was excluded. Gmelin and Tiedemann have recently arrived at the same results f. When air is present, the extrication of gas certainly does take place in the manner described in a sub- sequent part of this essay, where Dr. Stevens’ view of this matter will be noticed.] John Hunter concluded, from an ex- periment on the blood of a turtle, that neat is evolved during its coagulation; and notwithstanding the disparity of cases, this conclusion appears to have been extended to the coagulation of blood in general. The author of an article on Blood, in Rees’ Cyclopaedia, and more recently, Dr. Gordon J, (al- though their experiments are not quite conclusive), have rendered it probable that a slight evolution of heat attends the coagulation of blood, both arterial and venous, of warm-blooded animals. [Sir G. Scudamore confirms this state- ment. This evolution of heat is doubt- less the chemical result of the solidifica- tion of the liquid fibrine ; but the co- agulation of blood, and of lymph effused, as well as their fluidity in their proper vessels, are phenomena of living che- mistry, which wc do not yet understand. The reason of the fluidity of the blood assigned by Dr. Stevens, the presence of saline matter, is quite inadequate, for * Phil. Trans. 1818. + Pogemlorf Ammlen, xxxi. t Ann. of Philosophy, vol.iv. this undergoes no diminution or change during the few minutes which precede the coagulation ; and this phenomenon takes place whether the blood be ex- cluded from or exposed to the air. Warmth rather accelerates it; and Ber- zelius states that blood frozen before coagulation, will, on thawing, present the usual separation into crassamentum and serum*.] I shall now describe the nature and properties of the several component parts of the blood, as far as they have been investigated. Albumen is known to exist in two states; in that of a colourless glary fluid, as in the white of an egg, or in a more diluted state in the serum of the blood; and in that of a white opales- cent solid, varying in consistence ac- cording to the quantity of water with which it is united. Liquid albumen may be converted into this latter state by the operation of heat, galvanism, acids, and alcohol. The two latter have been supposed to produce this effect by abstracting the water which holds it in solution. The action of heat on albu- men has not been so readily explained. The opinion of Dr. Thomson is, that heat, by increasing’ the elasticity of the water and soda, which by a weak affinity hold albumen in solution, gives their particles a tendency to separate, and thus enables the particles of albu- men to obey the attraction of cohesion which exists among themselves, and thus to form a solid massf. This ex- planation, which appears to me equiva- lent to the expression, that the addition of a certain quantity of heat deprives water of the power of holding albumen in solution, would still leave the rela- tions of these bodies an anomalous excep- tion to a law, otherwise general—name- ly, that heat increases the solvent power of water. [The opinion given by Dr. Turner docs not appear to me more ex- planatory — “ that albumen combines directly with water at the moment of being secreted, at a time when its par- ticles are in a state of minute division ; but as its affinity for that liquid is very feeble, the compound is decomposed by slight causes, and the albumen thereby rendered cjuite insoluble. Silicic acid affords an instance of a similar pheno- menon];.” Now there is this marked * Trnit6 de Chlmie, t.vli. t System of Chemistry, vol. iv. p. 401. X Elements of Chemistry, 1834, p. D38.