1889-90.] Professor Crum Brown on Optical Activity. 183 
than that of -CO — 0 — C 2 H 5 , but not much less. Take now the 
case of dimethyl tartrate. This, like the acid, is right-handed, but 
yields with acetyl chloride a strongly left-handed dimethyl diacetyl- 
tartrate. From this we gather that the k of -O — CO — CH 3 is 
greater than that of -CO — O — CH 3 , although the two radicals are 
isomeric. 
Let us now consider the case of asparagine. We do not know 
which of the two formulse HO— CO— CH 2 — CH(NH 2 )— CO— NH 2 , 
and HO— CO— CH(NH 2 )— CH 2 — CO— NH 2 is that of asparagine; 
we shall here use the latter.* In potash solution this becomes 
K— 0— CO— CH(NH 2 )— CH 2 — CO— NH 2 , if there were no dis- 
sociation of the ions. Similarly in hydrochloric acid solution it 
becomes H— 0— CO— CH(NH 3 C1)— CH 2 — CO— NH 2 , also if 
there were no dissociation of the ions. Here of the two radicals 
— CO' — OH and -NH 2 the one is increased by dissolving the substance 
in potash, the other by dissolving it in hydrochloric acid ; and (as 
is well known) asparagine rotates to the left in alkaline, and to the 
right in acid solution. The case of aspartic acid is quite similar. 
Another case which has been pretty fully investigated is that of 
active amyl alcohol and its derivatives, t Active amyl alcohol has the 
constitution CH(C 2 H 5 )(CH 3 )(CH 2 OH) ; it is left-handed, as is also, 
to nearly the same extent, the corresponding amylamine. But the 
other derivatives, in which the fourth radical in our formula is in- 
creased (as the bromide, CH(C 2 H 5 )(CH 3 )(CH 2 Br), the hydrochloride 
of the amylamine, and still more the di- and tri-amylamines), are 
right-handed. From all of which we may conclude that the k of 
-CH 2 OH is less than that of -C 2 H 5 and greater than that of -CH 3 ; 
that the k of -CH 2 QH is very nearly equal to that of -CH 2 NH 2 , 
that the k of -CH 2 Br is greater than that of — C 2 H 5 . 
Active lactic acid and its salts have been examined in reference to 
their optical activity by Wislicenus.f He finds that active lactic 
acid rotates in the opposite sense from its salts — this would mean 
that the «c of -COOH is less than that of -CH 3 , so that the in- 
* I use these formulae, and not those in which asparagine is represented as 
a salt, because I am here dealing only with asparagine in alkaline or acid 
solution. 
t See Plimpton, Ohem. Soc . Jour., xxxix. 332 ; and Just, Liebig’s Ann., 
ccxx. 146. 
+ Liebig’s Ann., clxvii. 302. 
