4 THE POPULAR SCIENCE MONTHLY. 



Buffon names organic molecules. According to Buffon, the oak owes 

 all the peculiarities of its organization to the special oak-molecules of 

 which it consists ; and so all the differences in the vegetable or ani- 

 mal kingdom, from the lowest to the highest species, depend on fun- 

 damental peculiarities with which their respective molecules were pri- 

 marily endowed. There must, of course, be as many kinds of molecules 

 as there are different species of living beings ; but, while the molecules 

 of the same species were supposed to be exactly alike and to have a 

 strong affinity or attraction for each other, those of different species 

 were assumed to be inherently distinct and to have no such affinities. 

 Buffon further assumed that these molecules of organic Nature were dif- 

 fused more or less widely through the atmosphere and through the soil, 

 arid that the acorn grew to the oak simply because, consisting itself of 

 oak -molecules, it could draw only oak -molecules from the surrounding 

 media. 



With our present knowledge of the chemical constitution of organic 

 beings, we can find a great deal that is both fantastic and absurd in 

 this theory of Buffon, but it must be remembered that the science of 

 chemistry is almost wholly a growth of the present century, while Buf- 

 fon died in 1788 ; and, if we look at the theory solely from the stand- 

 point of his knowledge, we shall find in it much that was worthy of this 

 great man. Indeed, in our time the essential features of the theory of 

 Buffon have been transferred from natural history to chemistry almost 

 unchanged. 



According to our modern chemistry, the qualities of every substance 

 reside or inhere in its molecules. Take this lump of sugar. It has cer- 

 tain qualities with which every one is familiar. Are those qualities at- 

 tributes of the lump or of its parts ? Certainly of its parts. For, if we 

 break up the lump, the smallest particles will still taste sweet and show 

 all the characteristics of sugar. Could we then carry on this subdivi- 

 sion indefinitely provided only we had senses or tests delicate enough 

 to recognize the qualities of sugar in the resulting particles ? To this 

 question, modern chemistry answers decidedly : No! You would before 

 long reach the smallest mass that can have the qualities of sugar. You 

 would have no difficulty in breaking up these masses, but you would 

 then obtain not smaller particles of sugar, but particles of those utterly 

 different substances which we call carbon, oxygen, and hydrogen, in a 

 word particles of the elementary substances of which sugar consists. 

 These ultimate particles of sugar Ave call the molecules of sugar, and 

 thus we come to the present chemical definition of a molecule, " The 

 smallest particles of a substance in which its qualities inhere,'''' which, 

 as you see, is a reproduction of Buffon's idea, although applied to mat- 

 ter and not to organism. 



A lump of sugar, then, has its peculiar qualities because it is an 

 aggregate of molecules which have those qualities, and a lump of salt 

 differs from a lump of sugar simply because the molecules of salt differ 



