ODORS AND LIFE. 193 
concealed in matter make themselves known to us ina still 
more remarkable phenomenon, to which the name of isom- 
ery is given. Two bodies, thoroughly unlike as regards their 
properties, may present absolutely the same chemical com- 
position with respect to quality and quantity of elements. 
“ But in what do they differ?” it may be asked. They differ 
in the arrangement of their molecules. Coal and the dia- 
mond are identical in substance. Common phosphorus and 
amorphous phosphorus are one and the same in substance. 
Now, the odorous principles of plants offer some exceedingly 
curious cases of isomery. ‘Thus the essence of turpentine, 
the essence of lemon, that of bergamot, of neroli, of juniper, 
of savin, of lavender, of cubebs, of pepper, and of gilly- 
flower, are isomeric bodies, that is, they all have the same 
chemical composition. Subjected to analysis, all these 
products yield identical substances in identical proportions, 
that is, for each molecule of essence, ten atoms of carbon, 
and sixteen atoms of oxygen, as denoted by their common 
formula, O°H". We see how these facts as to isomery 
prove that the qualities of bodies depend far more on 
the arrangement and the inner movements of their minute 
particles, never to be reached by our search,‘than on the 
nature of their matter itself; and they show, too, how far 
we still are from having penetrated to the first conditions 
of the action and forces of substances. Among odoriferous 
essences placed by chemists in the class of aldehydes may 
be named those of mint, rue, bitter-almonds, anise, cummin, 
fennel, cinnamon, etc. The rest are ranged in the great 
series of ethers, which vary widely in complexity, notwith- 
standing the simple uniformity of their primary elements. 
Such is the chemical nature of most of the odorous 
principles of vegetablé origin. But chemistry has not 
stopped short with ascertaining the inmost composition of 
these substances; it has succeeded in reproducing quite a 
number of them artificially, and the compounds thus manu- 
