( 517 ) 



bisulphite compound. From 10 grams of thiotolcne about 5 grams of the aldehyde 

 are obtained. Of this, 3 grams are oxidised with 500 cc. of water containing 

 3.2 grams of potassium permanganate and 1.3 gram of 80 % potassium hydroxide ; 



after standing over night the liquid is filtered from the manganese dioxide, con- 

 centrated and acidified when about 3 grams of thiophenic acid are precipitated. 

 The dechlorination of this product with sodium amalgam in dilute aqueous solution 

 takes 15—20 days during which a large portion of the acid gets lost. 



As regards the solubility of ^-thiophenic acid at 25° it was found 

 that the saturated solution contains 0.43 °/ of a cid. 



Melting point line of mixtures of the two acids. According to the 

 present views of the phase rule it was natural to suppose that the 

 impossibility of separating these acids by crystallisation is due to 

 the fact that they yield mixed crystals. In fact by determining the 

 melting point line, Dr. Voerman has succeeded in demonstrating 

 with certainty that they give an interrupted mixing series. The 

 initial solidifying points may be observed very sharply but the final 

 solidifying points can only be determined within 0°.5. 



A list of the initial and final solidifying points is appended; and 

 in the annexed curve these figures are represented graphically. 



t 



HO 



135 ° 

 130 C 



m c 

 lko c 

 H5 l 



110 C 



ios l 



%/J 70 Z0 30 U0 



Fig 



to 



. 1. 



t 



JkO 



1 3$' 



730' 

 1Z5 { 



no 



115' 

 110 { 

 105 



60 90 100 /c/3 



r* 



