NEW CONCEPTIONS IN SCIE_NCE 



mite, either attracting or repelling bodies with 

 smashing force. 



If the precipitation of the gluelike solutions be 

 an electrical effect, and if the theory of electric 

 solutions be true, one might expect to find one of 

 the constituents of the salt that is, either the so- 

 dium or the chlorine, carried down with the glue 

 or the jelly. This is exactly what happens. The 

 electric theory was built up with infinite toil, and 

 the chain of reasoning upon which it rested was 

 beautiful to follow; but it is simple facts like this 

 which clinch it and make it tangible to the mind. 



These highly electrified particles seem to be the 

 atoms of the chemist. Behind the physical unit of 

 matter the molecule we have, therefore, the unit 

 of chemical combination the atom. The necessity 

 of such an assumption has so steadily increased 

 since the first crude conjectures of Dalton that to- 

 day it has become an integral part of all chemical 

 investigation. This is especially true of the chem- 

 istry of the products of life. Modern organic chem- 

 istry rests not merely upon the belief in the ma- 

 terial atom, but conceives for some of them a 

 definite shape. The atom of carbon, which is the 

 nucleus from which all living things and the prod- 

 ucts of all vital activity are formed, is pictured 

 as an asy metrical tetrahedron that is, simply, a 

 minute pyramid with unequal sides. If this seems 



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