Bartow—A Mechanical Cause of Homogeneity of Crystals. 595 
body possessing optical rotatory power contains an asymmetriccarbon 
atom,’ and that the optical activity disappears with the disappear- 
ance of the asymmetric carbon atom.’ 
The same kind of enantiomorphous grouplet may enter into 
the composition of various larger groups of different kinds, and 
show its presence by its characteristic properties. And if the 
dissimilar parts of the compared groups are identical with their 
own mirror-images, and consequently all the enantiomorphous 
properties are traceable to the portion which is identical in the 
different groups, the enantiomorphous properties of the latter may 
be expected to be very much alike. 
In connection with this we may recall the conclusion reached 
by Bouchardat that if the molecule of an optically active body 
when it enters into the composition of compounds is neither decom- 
posed or modified, the derivatives, like the body itself, are found 
possessed of rotatory power.? This conclusion is verified in the case 
of amygdalinic acid obtained from amygdalin, and in the case of 
-ecamphoric acid obtained from camphor.* 
Transition from one to the other of two enantiomorphously similar 
groupings. 
It is conceivable that considerable local disturbances may suffice 
to cause a fluctuation of the arrangement of a group without 
breaking the ties which bind its parts together, and thus that an 
asymmetric grouplet may continually be tossed from one to the 
other of two enantiomorphously-similar groupings which are closest- 
packed arrangements. The ultimate effect of this upon an assem- 
blage originally consisting entirely of asymmetric groups of one 
1 That is to say a carbon atom, the atom or atom-complexes associated with which 
present a diversity which leads, when the atoms are located in the way above described 
(note 1, p. 594), to an enantiomorphous form, #.¢., the molecule or complex containing 
the carbon atom is of the formula a dc d. 
2 Stéréochimie par van’t Hoff und Meyerhoffer, p. 28. 
3 Compt. Rend. 28, p. 319; Journal f. prakt. Chemie 47, p. 455; Annalen der 
Chemie 72, p. 168; Jahresb., 1849, p. 123. 
* Compt. Rend., 19, 1174 and 28, p. 319. 
When in cases of substitution, the directioa and amount of optical rotation show 
persistence during the conversion, it gives a clue to the discovery which of the atoms 
are concerned in the rotation, i.¢., which of them have an enantiomorphous grouping. 
(Comp. ‘‘ Hantzsch’s Grundriss &c.,’’ p. 53.) 
