514 Wisconsin Academy of Sciences, Arts, and Letters. 
result on the basis of an inversion with both reagents entirely 
analagous to the double inversion which Fisher seems to have 
rigidly established in the case of optically active valin. There 
is very little danger that McKenzie will contribute anything 
startling to our present knowledge of the Walden inversion’ as 
he is unquestionably simply following Fisher’s lead in another 
series. As a serious objection to McKenzie’s work he has yet to 
prove, as far as I can see, that his phenyl chloracetic acid, when 
treated and allowed to stand with solutions of various dilute al¬ 
kalies in cold water, 28 even by boiling finally for a short time (30 
to 60 minutes) actually splits to any considerable extent, or, 
if it does split completely, that he obtains quantitatively mande- 
lic acid. If very little splitting actually takes place, then Mc¬ 
Kenzie’s results for stronger alkalies in water solution are value¬ 
less while oxide of silver, at all events, may be very reasonably 
held to give a normal substitution product—a result at variance 
with the facts established by Fisher, Walden and others who 
have used this reagent. Inasmuch as mandelic acid is a. beauti¬ 
ful crystalline body, these crucial experiments, when carefully 
repeated, ought to give much more definite results than are ob¬ 
tained with malic and lactic acid since both of the latter give 
oily derivatives difficult to identify sharply. Of course it must 
be admitted that the introduction of the pheuyl group exerts a 
powerful influence, but it may be said in this connection that 
monochloracetic acid gives sodium and potassium salts which 
are very stable in water and alkaline solution 29 while the halo¬ 
gen, being in the a position, is very easily removed with silver 
oxide. 
As I have tried to point out, future progress in disentang¬ 
ling the ‘Walden inversion’ will depend not on establishing 
more analogous inversions in other series, for this will simply 
add to the confusion already existing. 
A rational explanation for the results obtained, where an in¬ 
version of optical activity appears to take place, will undoubt- 
28 j. L. C'h. Soc., May 1909, p. 782 et seq. Expt. part. 
29 Senter: J. L. Ch. Soc. Sec. 1909, 1827; Hoffman: Ann. 102, 6; 
Kekule: Ann. 105, 288. 
