THE BEGINNINGS OF LIFE. 87 



usually mixed with them, they do not admit of 

 fusion, much less of volatilization. To which add, 

 that they have not even that molecular mobility which 

 solution in water implies ; since though they form 

 viscid mixtures with water, they do not dissolve in the 

 same perfect way as do inorganic compounds. The 

 chemical characteristics of these substances are in- 

 stability and inertness carried to the extreme. . . . , It 

 should be noted, too, of these bodies, that, though they 

 exhibit in the lowest degree that kind of molecular 

 mobility which implies facile vibrations of the atoms 

 as wholes, they exhibit in a high degree that kind of 

 molecular mobility resulting in isomerism, which im- 

 plies permanent changes in the positions of adjacent 

 atoms with respect to each other. Each of them has 

 a soluble and insoluble form. In some cases there are 

 indications of more than two such forms. And it 

 appears that their metamorphoses take place under very 

 slight changes of conditions In these most un- 

 stable and inert organic compounds, we find that the 

 atomic complexity reaches a maximum : not only since 

 the four chief organic elements are here united with 

 small proportions of sulphur and phosphorus, but also 

 since they are united in high multiples. The peculiarity 

 which we found characterized even binary compounds 

 of the organic elements, that their atoms are formed 

 not of single equivalents of each component, but of 

 two, three, four, and more equivalents, is carried to 

 the greatest extreme in these compounds that take the 



