";138 Scientific Proceedings, Royal Dublin Society, 



when small amounts of acid are used errors are introduced, probably owing 

 to particles of the liquid adhering to the walls of the flask. - 



The experimental results are given in Table IV, and constant C in the 

 iormula has been determined : 



where IFa and TF,p are weights of acid and water, Ma and M,„ are molecular 

 weights of acid and water, C = ratio of vapour tensions at 100°. 



The constant G, when immiscible and unlike components are used, is 

 ratio of the vapour-tensions of the two substances. 



The constant has therefore been used to calculate the vapour tension of 

 lauric and myristic acids. The temperature of the liquid is taken as 100° — 

 the boiling-point of distilled water — because the amount of the acids present 

 and their insolubility in water render it improbable that they will affect the 

 temperature of boiling to any appreciable extent. 



On account of the relatively small amount of acid present, the vapour 

 pressure is taken as atmospheric. 



The calculated vapour tensions are lower for myristic than for lauric 

 acid. 



Table IV. 

 Lauric Acid. 



Composition of distillate. ■ C Vapour tension 



Water. Acid. (ealoiilated). 



30-11 0-0256 7-6 x 10"= 0-058 mm. 



Myristic Acid. 

 60-45 0-0327 4-3 x 10"' 0-033 mm. 



These results are the mean of several determinations. 



The Distillation of Aqueous Solutions of Phenols. 



For the estimation of phenols in aqueous solution the method due to 

 Messinger and Vortmanni was employed. 



The method consists in adding a known amount of standard iodine solu- 

 tion to the phenol at a suitable concentration in presence of approximately 

 three molecular proportions of sodium hydroxide, and heated to 60°. The 

 iodine is added until the liquid assumes a yellow colour, and a yellowish 

 curdy precipitate separates on shaking. The solution is cooled, diluted to a 



' Ber., 1889, 22, 2313. Cf. Bergault. J. Pharm. Chem., 1908, 28, 45. 



