certain Tartrate Solutions. 267 









Observed 



Specific 



Deviation 



Formula and amou 



nt oi 



rotation 



rotation 



from 



inactive salt. 





a 



[a] 



normal. 





















NaN0 3 





5gm. 



1-640 



8-214 



+ 3-485 



NaCH,0 2 



. 3H„0 



5 



1-405 



7-037 



+ 2-308 



Na 2 S0 4 





5 



1-679 



8-409 



+ 3-680 



KN0 3 





5 



1-420 



7-112 



+ 2 383 



KC-H.Oa 





5 



1-510 



7-563 



+ 2-834 



K0CO3 





5 



1-830 



9-166 



+ 4-437 



TLSO4 





2 



0-912 



4-568 



— 0-161 



We find here that without exception the potassium aiid 

 sodium salts produce a marked increase in the rotation. In 

 the case of potassium carbonate the rotation is nearly doubled 

 and suggests at once the behavior of potassium tartrate as the 

 active body. The combined tartaric acid in 5 grams of thallium 

 tartrate is equivalent to that in 2 grams of potassium tartrate, 

 and supposing that amount of this salt in solution we can write 

 the specific rotation 



[a] = 22°-90 



The actual specific rotation of the anhydrous salt is given by 

 Landolt for C = 11*6 as 



[a] = 28°-48 



while a slightly lower value is given by Krecke. It seems pos- 

 sible, therefore, to account for this large rotation by assuming 

 the presence of some neutral potassium tartrate. The other 

 inactive salts experimented with do not seem to have as great 

 a decomposing power on the tartrate, if this assumption may 

 be considered the correct one. It will be noticed that the 

 thallium sulphate decreases the rotation slightly. 



Thallium Bi-tartrate, HT1C 4 H 4 B . 



This salt was prepared by treating thallium carbonate with 

 an excess of tartaric acid. As it is but slightly soluble it was 

 easily freed from the excess of acid by crystallization and wash- 

 ing with water. 



I investigated only one solution, having a strength of l gm in 

 100 co , and found 



a = 0°-48 t = 20° 



[«]= 12°-02 



Thallium Sodium Tartrate, TlNaC 4 H 4 6 . 4H 2 0. 



This beautiful salt is readily produced by mixing solutions 

 of the acid thallium tartrate and sodium carbonate in equiva- 

 lent proportions and allowing to crystallize after sufficient con- 

 centration. Large crystals resembling those of Rochelle salt 

 are formed. They are, however, liable to break down by loss 

 of water of crystallization, unless kept in a perfectly close bot- 



