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IT'. €1. CONE AND I,. C. C.\DY
vanishes in the tertiary amines. From this he deduces tlie conclusion that this band represents the first overtone frequencv characteristic of the N-€1 bond, the fundamental band occurring near G.1p. He is led to this conclusion through tlie fact that animonirt has bands of ahsorption a t 6 . 1 and ~ 2.90,~. Although the measurcments by Eel1 on alkyl, benzyland phenylamines s h o a~ \-ariation in absorption near tip as well a5 distinct bands near 3 p , thus supportiny Salanf's hypothesis, the Iiypothesis receives no support in the case of the anilines, for no detectable change in absorption occurs at (ip. 'l'he author plans to extend the investigation t o a study of a number of al1,yl :mines, benq nines, phenylaniincs m t l alii? 1 naphthylaiiiines.
Summary 1. The infra-red absorptioii spectra below 2 . 8 ~ha\ c k e n rccordetl for aniline and ten mono- and dialkyl anilines by means of a self-registering
spectrograph. ~ 1 . 0 4 , ~arc associated \ ~ ; i i h 2. Absorption bands occurring a t 1 . 4 7 , ~and the presence of S i H bonds within the molecule, and these t d e n u i t h a band found by Bell a t 3.Sp are sliorvn to form a three-mcmbcrcd, parabolic frequency series. 3. h possible identification of bands near 2.Og and 1 2 p as coml)in,itions of K-H frequencies and CI fundamental C-FI frequency is suggested. LOS . k G € X E S , CL\LIFORNI.4
DIPHENYLBENZIDINE AS AE INTERNAL INDICATOR FOR THE TITRATION OF ZINC WITH POTASSIUM FERROCYANIDE B Y lv.H. C O X E A S D L. c. CADY RBCCIVSD SOVSXBER 1, 1026
PGBLISHLD I:ISIIRUARY 3 , 1027
Xt present there is no suitable internal indicator for the titration of zinc with potassium icrrocpanide. The authors have Ixen able to find only one inside indicator suggested for this titration, namely, t h z use of ferrous sulfate 131- Scott.' This indicator had )iceti suggested for use only in the titration of zinc ores prepartd for analysis by t!ie hydrogen sulfide methoti, in w.hich case there are no oxidizing agents present. Uranium nitrate, the icdicator largely iised a t present, has the disadvantage of being an external indicator. Much time is required to determine the exact end-point and an error is introduced in removing portions of the solution for testing. At best, the titration must proceed slon-ly and a blank corrcction l,c applictl to tlie voluriic of titrntitig solution rcquircd. ,, 1 1 1 iisc ~ of tliplicr:! I x i i i i i i ( , or ~ ~ i ~ ~ I i ~ : i ~ . lns~ ;i i~~ ~t l ! i ; ~ i ~ ~ ~ : ~ c 2
Fcott, "Si:iiitianl .\f
