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Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. CHEMISTRY AND PHYSICS. 



1. Some Experiments in Electro-physiology; by Prof. Mattetjcct, in 

 a letter to Dr Faraday, dated May 1, 1856, (Phil. Mag. [4], xi, 461.) — 

 I think I have already told you that for some time past I have been 

 making experiments in electro-physiology. Allow me now to communi- 

 cate to you the results of my work. 



I have lately succeeded in demonstrating and measuring the phenome- 

 non which I have called muscular respiration. This respiration, which 

 consists in the absorption of oxygen and the exhalation of carbonic acid 

 and azote by living muscles, and of which I have determined the princi- 

 pal conditions and intensity compared with that of the general respiration 

 of an animal, has been studied particularly on muscles in contraction. I 

 have proved that this respiration increases considerably in the act of con- 

 traction, and have measured this increase. 



A muscle which contracts, absorbs, while in contraction, a much greater 

 quantity of oxygen, and exhales a much greater quantity of carbonic acid 

 and azote, than does the same muscle in a state of repose. A part of the 

 carbonic acid exhales in the air, the muscle imbibes the other part, which 

 puts a stop to successive respiration and produces asphyxy of the muscle. 

 Thus a muscle soon ceases to contract under the influence of an electro- 

 magnetic machine when it is enclosed in a small space of air ; this cessa- 

 tion takes place after a longer interval of time if the muscle is in the open 

 air, and much more slowly still if there be a solution of potash at the 

 bottom of the recipient in which the muscle is suspended. Muscles which 

 have been kept long in vacuum or in hydrogen are nevertheless capable, 

 though in a less degree, of exhaling carbonic acid while in contraction ; 

 this proves clearly that the oxygen which furnishes the carbonic acid ex- 

 ists in the muscle in a state of combination. According to the theories 

 of Joule, Thomson, <fcc, the chemical action which is transformed, or 

 which gives rise to heat, is also represented by a certain quantity of vis 

 viva, or by an equivalent of mechanical work. I have therefore been able 

 to measure the theoretical work due to the oxygen consumed, taking the 

 numbers which I had found for muscular respiration during contraction, 

 and in consequence the quantity of heat developed by this chemical ac- 

 tion, and finally this theoretical work according to the dynamical equiva- 

 lent of heat. I have compared this number with that which expresses 

 the real work which is obtained by measuring the weight which a muscle 

 in contraction can raise to a certain height, and the number of contrac- 

 tions which a muscle can perform in a given time. It results from this 

 comparison, that the first number is somewhat greater than the second, 

 and the heat developed by contraction ought to be admitted among the 

 causes of this slight difference : these two numbers are therefore suffi- 

 ciently in accordance with each other. 



I have completed these researches by some new studies on induced contrac- 

 tion, that is to say, on the phenomenon of the irritation of a nerve in con- 

 tact with a muscle in contraction. A great number of experiments lately 



