STANISLAO CANNIZZARO 



By M. M. PATTISON MUIR 



The death of the greatest of philosophical chemists at Rome, 

 on May 13 of this year, bids those who are engaged in 

 building up the science advanced so greatly by him to consider 

 the work which Cannizzaro did in clarifying and realising for 

 himself and them some of the fundamental conceptions of 

 chemistry. 



The lifetime of Cannizzaro covered the greater part of the 

 period of the development of modern chemistry. Born at 

 Palermo in 1826, had he lived two months longer he would 

 have completed his eighty-fourth year. 



In order to understand the work of Cannizzaro, and to form 

 a just estimate of the relations of it to the general progress of 

 chemistry, it is necessary to consider briefly the position of 

 each of the departments of chemical thought whereon his work 

 shed light, at the time, 1858, when his greatest contribution to 

 chemical philosophy appeared. 



By showing chemists how to use them, Lavoisier gave 

 definite meanings to three conceptions — chemical interaction, 

 composition, element. Eighteen years before the birth of 

 Cannizzaro, Dalton gave to chemistry an instrument for 

 applying, minutely and intimately, to all particular cases of 

 material change wherein composition and properties alter simul- 

 taneously, the ideas which Lavoisier had clarified and begun 

 to use. Dalton laid hold of the atomic speculation of the 

 Greeks, attached it to particular instances of a certain limited 

 kind of material change, and added to it a method which 

 changed it from a vague, qualitative view into a quantitative 

 scientific theory. Dalton began the work of determining the 

 relative weights of atoms. 



The path opened by Dalton soon led him into a difficulty 

 which neither he nor others could overcome. He saw clearly 

 that before a value could be selected from the several possible 

 values of the atomic weight of oxygen, it was necessary to 



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