AN IMPROVED COLORIMETER FOR COLOR INHERI- 

 TANCE STUDY 



HERBERT F. ROBERTS 



University of Manitoba, Winnepeg, Manitoba 



The necessity for an improved standard type of colorimeter 

 available for the quantitative study of color values has long 

 been felt by workers in plant physiology and in genetics. Sev- 

 eral types of color apparatus are now upon the market. The 

 writer's experience has been with the type known as the tintom- 

 eter, an apparatus which has long been quite generally employed 

 for commercial purposes, and which is in use at several of the 

 experiment stations in the United States. Finding the original 

 instrument unsatisfactory from certain standpoints, the writer 

 undertook a series of experiments in its reconstruction and mount- 

 ing which may be of value and interest to geneticists and others 

 engaged upon problems involving colorimetric determinations. 



In substance the original instrument is a binocular of wood, 

 supported in an inclined position. The object, the color of 

 which is to be determined, is placed in a hollow tray under the 

 right hand tube of the binocular. Under the left hand tube is 

 placed a similar tray containing chemically pure calcium sulfate, 

 intended as a standard white reflecting surface. In the end of 

 the left hand tube of the binocular is fitted a small rack into 

 which certain colored glass strips are placed. These are made up 

 in graded intensities of the three primary colors, and are alter- 

 nately placed in the rack until such an adjustment of the three 

 colors is reached as gives a combined color effect to the left eye, 

 similar to that produced on the right eye by the colored rays 

 proceeding from the object itself. These colored glasses bear 

 no direct relation to the spectrum colors, but are founded as a 

 base on the colors produced by fractional normal solutions of 

 three different chemical compounds. The glass of each of the 



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