396 



WHERRY AND ADAMS: PINAVERDOL 



not too elongated forms. Experiments are now being carried on 

 to verify these relations and the preliminary results indicate the 

 correctness of the equation for all ratios of R/d. This part of the 

 work will be published separately in the near future. 



CRYSTALLOGRAPHY.— 7/z^ crystallography and optical 

 properties oj the photographic sensitizing dye, pinaverdol. 

 Edgar T. Wherry and Ei^iyioT Q. Adams, Bureau of Chem- 

 istry. 



CHEMISTRY 



Pinaverdol is the trade name of a synthetic dyestuff^ related 

 to quinoline, and used to sensitize the silver halide^ of photo- 

 graphic plates to green and yellow light. Its structure is indicated 

 by the name "i,i',6'-trimethyW5c-cyanine iodide." "Cyanine 

 iodide" is a tautomeric form of the hydriodide of 4,4'-diquinolyl 



1' ^ 



f f ? 



5 4 



8 N 



Quinoline 



4,4-olicjuinolyl methane 



:yknip>e Iodide .^o-CvAoine lodiJe RnRverdo 



1 A full description of the preparation and properties of this substance will appear 

 in the Journal of Industrial and Engineering Chemistry. 



2 "Halide" is a general term comprising chloride, bromide, and iodide, i. e., 

 binary salts derived from any of the halogens. 



