483 



we shall remember a man who by his talents conferred the greatest 

 benefits on the civilized world, — who endowed inanimate machinery 

 with the means of rapidly passing over the greatest distances by 

 land, and of overcoming the force of adverse winds upon the ocean, 

 — who brought to perfection the most important mechanical power 

 with which man is yet acquainted, if indeed we are ever to see it 

 surpassed : finally, a man who united the science of the profound 

 philosopher to the ingenuity of the original inventor. 



I am sure that the Society will unite with me in the expression 



has never before possessed. The Council consider these researches relating 

 to atomic weights, which he has since extended to other elements besides 

 carbon, as highly interesting and as greatly enhancing the claim of M. 

 Dumas, derived from his memoirs on chemical types, to the distinction of 

 the Society's Copley Medal. That claim he has again increased by the 

 more recent investigations he has undertaken of the most delicate and im- 

 portant nature, in the two several departments of inorganic and organic 

 chemistry. 



The first of these embraces the analysis of air, and the composition of 

 water ; inquiries remarkable for the novelty and exactness of the methods 

 of analysis, the time and pains bestowed upon them, and the minute accu- 

 racy of the results. These new analyses now form the most fundamental 

 determinations in the science. The superior accuracy of M. Dumas's 

 analysis of water may be estimated from the circumstance, that while, by 

 the last determinations lately received, namely, those of Berzelius and of 

 Dulong, the proportion of oxygen to 1000 parts of hydrogen was ascer- 

 tained only between the limits of 7930 and 8042, the new determinations 

 limit the proportion of oxygen betwen 8000 and 8003. "While the old 

 determinations also were deduced from no more than three analyses, the 

 new determinations are deduced from nineteen separate operations. The 

 exactness introduced by M. Dumas into the analysis of air is equally re- 

 markable, and the ultimate result is deduced from not less than one hundred 

 elaborate analyses of air made by that chemist and his pupils during various 

 seasons of the year and in different quarters of the globe. 



In the same inquiry, the object of which is to furnish chemists with 

 analytical constants of the highest attainable numerical accuracy, are in- 

 cluded new determinations of the atomic weights of several other elements 

 besides oxygen, hydrogen and nitrogen, the elements of air and water ; 

 particularly of carbon, to which reference has already been made. These 

 results possess peculiar interest, from confirming a theory which was pro- 

 mulgated many years ago by Dr. Prout, and uniformly supported since its 

 publication by several chemists of this country, although not assented to 

 abroad ; namely, that the atomic weights of all other elements are whole 

 numbers, or are multiples of hydrogen. This law M. Dumas has lately 

 extended to chlorine, silver, lead, calcium, potassium and sodium. 



The new researches of the same chemist in the department of organic 

 chemistry have reference to the composition of the great alimentary prin- 

 ciples of the animal economy ; namely, albumen, fibrin, casein and gelatin, 

 with their origin in plants, and also the origin of the fat of animals. The 

 memoir which contains these inquiries is a model of chemical research, 

 equally remarkable for its extent, accuracy and completeness. 



The recent discoveries of M. Dumas have procured for their author, in 

 his own country, the high distinction of President of the French Academy, 

 and of being the successor of Lacroix as Dean of the Faculty of Sciences 

 in the University of Paris. 



