264 J. II long — Circular Polarization of 



Art. XXXYIII. — On the Circular Polarization of certain 

 Tartrate Solutions — II ; by J. H. Long. 



My first experiments on the circular polarization of tartrate 

 solutions were described in the number of this Journal for 

 November, 1888, volume xxxvi, page 351. (See also Chemical 

 jSIews, December, 1888, page 313). It was there shown that 

 the rotation of solutions of potassium sodium tartrate is changed 

 by the addition of various inactive salts, being increased by salts 

 of potassium and ammonium, and decreased by salts of sodium, 

 lithium and thallium, with the decrease in the last case espe- 

 cially marked. In this paper I describe experiments carried out 

 with other tartrates. In these later investigations I have em- 

 ployed the large Landolt polariscope made by Schmidt & Hsensch 

 using the 400 mm tube. As the specific gravity of the solutions 

 tested was found in nearly every case I have usually employed 

 in the reductions, the formula 



3 > 



[a]= 



instead of the simpler one 



10 4 a 

 LRD 



r , . 10 a 



w = LC ' 



where a is the observed angle of rotation, L the length of the 

 tube in millimeters, C the concentration, or number of grams 

 of active substance in 100 cc , all weights being reduced to vacuo, 

 D the specific gravity of the solution referred to water at -4°, 

 and P the per cent, by weight, of active substance in solution. 



Potassium Antimony Tartrate, K(SbO)0 4 H 4 O 6 . ^Hfi. 



For a study of this salt a preparation from Schuchardt was 

 purified by several crystallizations. The tests, at 20°, gave, 



c = 2, a— 11°236 



c 4, a 22-545 



c . 5, a 28-207 



c 6, a 33-880 



In calculating [a] a slight correction has been introduced 

 because of the fact that the measuring flask employed in 

 making the solutions held 10O17 c0 instead of 100 cc . 



It will be noticed that there is a slight increase in the specific 

 rotation by increase in concentration. By increase of temper- 

 ature there is, however, a decrease. For t = 28° I found 

 [a] — 139 0, 92, taking into consideration the change in density 

 of solution. 



a 



= 140-688 



a 



141-144 



a 



141-273 



a 



141-404 



