EHRENBERG ON ORGANIC xMOLECULES AND ATOMS. 569 



have become rather too bold. Not content with regarding atoms as 

 ideal unities, or as indefinitely small magnitudes, we have endeavoured 

 to find for individual atoms or for certain minute groups of them an 

 expression of a proximate finity, and even to fix its magnitude and to 

 determine it by numbers. Indeed it appears that but little is wanting 

 in our days to induce bold theorists to attack in good earnest the ma- 

 terial primitive jiarticles of bodies, to clutch them fast, and to build 

 up with them even to organic structures, and thus to sport with them. 



Newton indeed thought he might assume the elementaiy particles of 

 colours in bodies of a certain magnitude and perceptible to sense. He 

 says, p. 64, Prop, vii., " For if those instruments (microscopes) are or 

 can be so far improved as with sufficient distinctness to represent ob- 

 jects five or six hundred times bigger that at a foot distance they ajipear 

 to our naked eye, I should hope that we might be able to discover some 

 of the greatest of those corpuscles. And by one that would magnify 

 three or four thousand times, perhaps they might all be discovered, 

 but those which produce blackness." If we now suppose that Newton 

 had rightly estimated the natural acuteness of the vision of the human 

 eye, his elementary particles for the red colour must not amount to less 

 than gg^(,(j of a line in diameter, as will be seen lower down ; and 

 between this magnitude and that of 1:^4,0770 all the elements of colours 

 except black would be found. It is however probable that Ne\vton sup- 

 posed the power of vision of the human eye to be less, and therefore 

 the size of the elementary particles to be much greater. However 

 we must here not forget, as Herschel has already remarked in his Optics, 

 that Newton distinguished the elementary particles of colours from 

 atoms, as later philosophers have also done, although he does not ex- 

 press himself to that effect. In that passage Newton does not speak of 

 atoms but of colouring particles. (Newton's Opticks (ITOi), book ii. 

 part iii. Prop. vii. p. 64. 



The small magnitudes which have been employed for the explanation 

 of the phaenomena of light in the undulatory theoiy give a great defi- 

 niteness to the calculation ; they can however only be regarded as 

 hypothetical and not as real demonstrated magnitudes, as the whole 

 theory, even though it possesses great probability, is in want of full 

 confirmation. The smallest lengths of a wave of light which can be 

 shown by an exact calculation, do not amount to more than the yooWo 

 of an inch, or about -^-j^jy^ of a line. Now as the particles of aether 

 must be considerably smaller than their undulations, there is in that 

 number a limit, arbitrary indeed, but yet determinate, for its maximum, 

 which gives an expression for its smallness. If from the impondera- 

 bility of very great condensed masses of light or of fether we were to 

 form a conclusion as to the smallness of the elementary coqiuscles ns 

 ponderable obj(!Cts, we should be obliged to place the limits of that 

 maximum at a still much greater dist;uice. All these however, even 



