270 J. H. Long -Circular Polaris ah on of 



solutions containing potassium antimony tartrate, when the 

 conditions of preparation were the same. 



This behavior suggests a most interesting field of inquiry, 

 viz : What in general is the behavior on polarization of solu- 

 tions in an unstable condition of equilibrium ? For example, 

 a solution of potassium antimony tartrate, with a chloride 

 may be called stable, as there is no precipitation at any temper- 

 ature, but with iodides and many oxygen salts only dilute 

 solutions can be made clear, and these remain so but a short 

 time and at low temperatures. 



The solutions prepared with acetates decompose, if heated, 

 precipitating antimonious oxide or a basic salt, and leaving a 

 simple tartrate in solution, which would now, of course, show 

 a diminished rotation. The diminished rotation without pre- 

 cipitation suggests that even with solutions prepared in the 

 cold some change has already taken place. 



It is likewise worthy of note in the above table that the 

 solutions with ammonium nitrate, ammonium sulphate and 

 sodium sulphate show a further reduction by increase in the 

 amount of inactive salt added. 



Thallium, Potassium Tartrate, T1KC 4 H 4 6 . 

 The solutions used were prepared by weighing out equivalent 

 portions of thallium bitartrate and potassium carbonate, suffi- 

 cient to furnish 5, 10, 15 and 20 grams of the anhydrous salt 

 in 100 c c. The crystallized salt is not made as readily as the 

 corresponding sodium compound. Mixed salts with variable 

 amounts of water of crystallization are usually obtained, and 

 to avoid any uncertainty as to the composition of the crystals 

 I prepared the solutions as just described. Four solutions 

 were tested, the results of which are found below. A curve 

 showing the rate of change in the specific rotation is shown at 

 B in the figure. 



gm. inlOOcc. D 2 4 ° P a [a] 



5 gm. T1KC 4 H 4 6 1-0377 4-810 2-008 10-057 



10 " " " 1-0764 9-274 3"530 8-840 



15 " " " 1-1143 13-437 5-010 8-365 



20 " " " 1-1530 17-316 6"527 8-173 



Attention may be called to the influence of temperature 

 here. For a solution containing 10 gm. of the salt in 100 c. c. I 

 find ■ 



[a] 20 =8°-840 

 |_a] M = 10-092 



The increase for 1°C. here is o- 125 in sp. rotation, while for 

 the sodium compound corresponding I found o- 112. 



As indicating the effect of addition of inactive salts, I found 

 for a solution containing in 100 c. c. 10 gm. of the tartrate and 



