J. H. Long — Polarization of Tartrate Solutions. 355 



Formula and amount of inac- 

 tive salt added to 20°-m. of 

 KNa C 4 H 4 6 .4H 2 in lOOcc. 



KSCy 5 



KSCy 10 



KSCy 15 



KSCy . 20 



KC 2 H 3 2 5 



KC 2 H 3 0. 2 10 



KC0H3O0 15 



Observed 

 rotation 

 a 

 8-994 

 9-030 

 9-075 

 9-134 



KC,H s 2 

 K 2 S0 4 __ 



20 



K 2 S0 4 10 



K 2 C 2 4 . H 2 5 



NH 4 C1... 5 



20 



NH 4 C1_ 



NH 4 Br 5 



NH 4 Br 15 



(NH 4 ) 2 C 2 4 .H 2 0___ 5 



NH 4 SCy 10 



008 

 093 

 160 

 248 



040 

 094 



030 



033 

 239 



98? 

 093 



004 



036 



Specific 

 rotation 

 [a] 

 22-48 

 22-58 

 22-69 

 22-83 



22-52 

 22-73 

 22 90 

 23-12 



22-60 

 22-73 



22-57 



22-58 

 2310 



22-47 

 22-73 



22-51 



22-59 



Deviation 



from 

 Xormal. 



4- -38 



4- -48 



4- -59 



+ -73 



+ -42 

 + -63 

 4- -80 

 + 102 



4- -50 

 4- -63 



4- -47 



4- -48 

 4-1-00 



4- -37 

 4- -63 



4- "41 



4- -49 



A simple inspection of the table shows immediately several 

 important points. The addition of the sodium salts, without 

 exception, causes a decrease in the rotation, which is greater as 

 the amount of inactive salt is increased. The behavior of the 

 thallium salt is interesting ; here a remarkable change is pro- 

 duced. Experiments now in progress promise to throw some 

 light on the action of thallium compounds in parallel cases. 

 The addition of potassium and ammonium salts, without excep- 

 tion, increases the specific rotation. This deviation becomes 

 greater as more of the inactive salt is added. We have here a 

 remarkable difference between the sodium, thallium and lithium 

 compounds on the one hand and the potassium and ammonium 

 compounds on the other. These peculiarities may sometimes 

 be applied in the quantitative analysis of salt mixtures. These 

 characteristic points and the amount of variation can be most 

 conveniently shown by curves in which the abscissas are the 

 amounts of inactive substance in solution with 20 gm of Kochelle 

 salt and the ordinates the specific rotation of the mixture, or 

 better, the deviation of this from a simple water solution of the 

 tartrate. 



I have drawn the curves given in fig. 1 on this plan. It 

 will be observed that some of them are practically straight lines 

 which can be represented by a simple equation of the form 



[a] = (a), + Ag, 



in which g is the amount of inactive substance in solution, and 

 (a\ the calculated rotation when g = 0. It might appear that 

 this value should be the same as that observed for the pure tar- 

 trate solution, but I think that does not necessarily follow. 



