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Medical Society (1823), afterwards published as a separate thesis, 

 entitled " On the Blood and its Changes by Respiration and Secretion," 

 embodying the views of Lagrange modified by farther research., in 

 the three following propositions : — 



1. The difference in composition between arterial and venous blood 

 consists chiefly in this, that the former contains an additional quantity 

 of oxygen, and the latter of carbonic acid, chemically united with it ; 

 the affinity between the blood and the oxygen being more powerful 

 than between the blood and carbonic acid. 



2. The oxygen gas of the respired air, pervading the walls of the 

 pulmonary vessels, displaces by virtue of its superior affinity an equal 

 bulk of carbonic acid gas, and thus converts venous into arterial 

 blood. 



3. In the course of the circulation, the oxygen thus absorbed 

 gradually attracts carbon from the proximate principles of the blood, 

 and uniting with it produces heat, and by thus also forming carbonic 

 acid converts the blood from arterial into venous. 



The second part of the essay is devoted to the subject of animal 

 heat, and Sir Benjamin Brodie's experiments are referred to and 

 commented upon. 



The author thinks that in this essay, written in 1823, he may be 

 allowed to have anticipated by many years some of the views of 

 Dumas and Liebig with regard to the changes in the blood through 

 respiration. 



Soon after taking the degree of M.D. at Edinburgh, Dr. Williams 

 went to Paris, and there became acquainted with the physiologist 

 Majendie, and saw many very eminent men of science, as La Place, 

 Yauquelin, Ampere, Humboldt, Cuvier, Arago, Gay- Lussac, &c, and 

 at the commencement of the Medical Session determined to make 

 the Hospital of La Charite and the Clinique of Laennec the chief 

 field of his work. An interesting description is given of Laennec, his 

 slim frame, his weakness, coupled, however, with quickness of per- 

 ception and intelligence, which enabled him to discover a new system 

 and art for the elucidation of disease. Dr. Williams remarks that 

 his teaching was little valued by the French students, and that his 

 class chiefly consisted of foreigners and but a sprinkling of his own 

 countrymen, these latter being more attracted by the impetuous 

 Broussais, who captivated them by his grand ideas and sweeping 

 hypotheses without troubling them with dry details or the results of 

 careful observations. Dr. Williams also speaks most warmly of the 

 knowledge of pathological anatomy which he obtained from Audral, 

 and remarks that in eight months he learnt more of the subject than 

 he could have done in eight years in the hospitals of his own country. 

 Chomel and Louis were also his instructors, and there can be no 

 doubc that his studies in Paris at this time had a great influence on 



