JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. VI JANUARY 19, 1916 No. 2 



PHYSICS. — The constants of the quartz-wedge saccharimeter and 

 the specific rotation of sucrose. Part I: The constants for 

 the 26 gram normal weight. 1 Frederick Bates and 

 Richard F. Jackson, Bureau of Standards. (Communi- 

 cated by G. K. Burgess.) 



The control of the quartz-wedge saccharimeter has previously 

 been based upon the experimental work of Herzfeld 2 and Schon- 

 rock. 3 The former prepared pure sucrose and determined the 

 sugar equivalents or values of a number of carefully selected 

 quartz plates, making the comparison upon quartz-wedge sac- 

 charimeters illuminated by Welsbach gas mantles, the light of 

 which was filtered through a potassium bichromate solution. 

 The rotations of these plates were then measured by Schonrock 

 in terms of the D lines of the sodium spectrum. These measure- 

 ments showed that the normal quartz plate caused a rotation 

 of 34? 657 at 20 ?0 C. The normal quartz plate is one which 

 causes the same rotation on the saccharimeter as the normal 

 sugar solution which is the fundamental basis of standardiza- 

 tion. The rotation of the normal plate in terms of monochro- 

 matic light is designated the Conversion Factor because it may 

 be used to determine the sugar value of any other quartz plate 

 whose rotation in terms of monochromatic light is known. 



1 The complete paper will appear in the Bulletin of the Bureau of Standards. 



2 Zs. Ver. Zuckerind. 50: 826. 1900. 



3 Zs. Ver. Zuckerind. 54: 521. 1904. 



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