proceedings: chemical society 113 



E. A. Hill, Patent Office: Van't Hoff's principle of optical super- 

 position. The lactonic constitution of the aldose sugars and the mela- 

 saccharins and the constants from which their specific rotatory powers can 

 be computed. 



By a comparison of the experimental values with the values of the 

 specific rotation computed on the basis of certain assumptions as to 

 constitution and structure, it is shown: 



1. That in carbohydrates and their derivatives having a plurality 

 of asymmetric carbon atoms, more particularly the aldose sugars 

 (provided we assume the modern 7-oxidic or lactonic ring theory of 

 their structure), the specific rotation [a\d is the algebraic sum of certain 

 constants corresponding to such asymmetric atoms so that, if A, a, /3, 

 7, 8, etc., be the constants for a given group of active isomers, the 

 specific rotation will be given by the formula; 



[a] d = ±.4±a±/3±7±5 . . . 



2. That Van't Hoff's so-called principle of optical superposition is 

 therefore valid for these cases. 



3. That the 7-oxidic or lactonic ring theory of these sugars, which 

 has been used to explain the phenomenon of mutarotation, is thereby 

 confirmed. 



The agreement between observed and computed values is very sat- 

 isfactory in each of the five groups presented. Thus, in both the 

 aldopentose and aldohexose sugars the maximum difference does not 

 exceed 1 per cent and the average difference is 0.1 per cent of the ob- 

 served values. 



The methods used for computing the constants are: 1st, a strictly 

 algebraic method; 2nd, a method similar to that used by Dr. Hudson 

 in computing his quantity A and which is as follows: When the 

 structural formulas of two active isomers differ only in the configura- 

 tion of one and the same asymmetric atom, the algebraic difference of 

 their specific rotations will be twice the value of the constant of such 

 atom. 



The 261st meeting of the Society was held in the Assembly Hall 

 of the Y. M. C. A. Building, May 11, 1916. Amendments to the con- 

 stitution were adopted abolishing the office of first and second vice- 

 presidents, the present incumbents to become members of the Execu- 

 tive Committee, the membership of which was increased to six elected 

 members. Mr. F. C. Cook was elected member of the Executive Com- 

 mittee to succeed H. M. Loomis, retiring from the section. The fol- 

 lowing resolution presented by a special committee consisting of J. A. 

 LeClerc, J. T. Keister, and H. S. Bailey was adopted: 



In the death of Prof. George E. Patrick the Chemical Society of Washington 

 has lost one of its oldest members. Professor Patrick was ever a faithful attend- 

 ant at its meetings and frequently took an active part in the discussions. 



