VI 11 



1835 to 1841. His election into the Royal Society is dated February 13, 

 ]845. 



Cesar Mansuete Despretz was born at Lessines in Belgium, on the 

 13th of May 1789. At an early age he came to Paris for the purpose of 

 devoting himself to the study of chemistry and physics. His intelligence 

 and industry soon attracted the attention of Gay-Lussac, who appointed 

 him repetiteur of his course of lectures on Chemistry at the Ecole Poly- 

 technique. He became the Professor of Physics at the Sorbonne in 1837, 

 having previously held a similar office in the Ecole Polytechnique and the 

 College Henri IV. In 1822 the Academy awarded him the prize for the 

 best memoir on the causes of animal heat. In 1825 he published an 

 elementary treatise on Physics, which in 1836 reached a fourth edition; 

 and in 1830 the Elements of Theoretical and Practical Chemistry. He was 

 the author of numerous memoirs published in the 'Annales de Chimie' 

 and in the *Comptes Rendus,' dating from 1817 up to 1858. These 

 memoirs give an account of researches on the specific heat and conductivity 

 of metals and various mineral substances ; on the propagation of heat in 

 liquids ; on the transmission of heat from one sohd body to another ; on 

 the heat absorbed in fusion ; on the elastic force of vapours ; on the density 

 and latent heat of vapours ; on the compressibility of liquids ; on the 

 density of gas under different pressures ; on the displacement and oscilla- 

 tions of the freezing-point of the mercurial thermometer ; on the heat 

 developed during combustion ; on the expansion of water, and the tempera- 

 ture at which water and saline solutions attain a maximum density ; on the 

 modifications which metals undergo under the joint action of heat and 

 amraoniacal gas ; on the chemical action of voltaic electricity, the light and 

 heat of the voltaic arc, and the intensity of the voltaic current ; on the 

 electricity developed by muscular contraction ; on chloride of boron ; on 

 the decomposition of water, carbonic acid, and acetic acid ; on the decom- 

 position of salts of lead ; on the limits of high and low musical notes ; on 

 the fusion and volatilization of some refractory substances under the triple 

 action of the voltaic battery, the sun, and the oxy hydrogen blowpipe. 



Though not successful in making any brilliant theoretical discoveries, the 

 important scientific facts he has observed and arranged bring his name 

 perpetually before the reader of any modern treatise on Physics. He 

 laboured hard to fulfil to the utmost his duties as a Professor at the Sor- 

 bonne ; and his lectures, being carefully prepared and well illustrated by 

 experiments, attracted a numerous auditory. He was elected a Foreign 

 Member of this Society in 1862. 



His character was upright and benevolent, his tastes simple, and his 

 habits regular in the extreme. It was his custom every year to make a 

 long excursion in England, Germany, or Italy, by himself, and without 

 letting any one know the day of his departure from Paris. 



His last illness was preceded by several slight attacks of cerebral con- 



