276 J. E. Long — Polarization of Tartrate Solutions. 



or one-twentieth of the molecular weights expressed in grams. 

 This would correspond to a solution of 107 gm. of KBOC 4 H 4 6 

 in lOOcc. that is an amount near what was taken for one of 

 the tests described some time back. 

 I found for 2=20° 



a=28°-14 



Considered as a solution of potassium sodium tartrate this gives 



[«] — 49°-89 + 



which is over twice the normal specific rotation of that salt. 

 But considered as a solution of 10 - 7gm. of potassium boro-tar- 

 trate it gives 



[a] = 65°-74 + 



which agrees very well with the other experiment. The value 

 is a little greater than was found for the pure boro-tartrate. 



That a decomposition of this sort takes place is shown also 

 by the taste and reaction of a solution of potassium boro-tar- 

 trate and sodium chloride. 



It seems, therefore, that we can look upon this as a case of 

 very interesting substitution with liberation of boric acid, 

 whose behavior with tartrates was long ago pointed out by 

 Biot and others, and more recently by Landolt (Berichte, 1888, 

 p. 191, and Fres. Zeitschr., 1889, p. 233). 



While these experiments do not by any means explain the 

 matter, tliey show that what, on first view, might be considered 

 as something apart, is in reality but a special case of a well 

 known phenomenon. Gernez has succeeded in isolating sev- 

 eral complex bodies from solutions showing a greatly increased 

 specific rotation, made by mixing tartaric acid with molybdates 

 (Berichte, 1888, Eef. p. 251 an<T773). It is possible that boric 

 acid and tartrates form in solution some such complex com- 

 pounds whose rotation is greatly in excess of that of the simple 

 tartrate alone. 



Considering the peculiar behavior of the antimony com- 

 pounds with carbonates, phosphates and acetates and of the 

 boro-tartrates with various inactive substances it is plain that 

 we have what may prove a fruitful method for the study of 

 changes in chemical equilibrium. The experiments given 

 above indicate the direction in which further work should be 

 prosecuted on this topic. In another communication I expect 

 to give especial attention to the question of unstable solutions, 

 and also to that suggested by the experiments of my first 

 paper, a study of the action of varying amounts of a few salts 

 on some one tartrate. 



Chicago, June 1, 1889. 



