3S4 



of these ionic coiidiie'li\ities i« 326. This ntiinber may be derived 

 in another way. H. E. Jones gives 380 as the limiting value for 

 HF at 25°. The valne as calculated above for 18' is 364. The 

 ditference per degree is 2.3 units, hence the value at 0° is 324. 

 The approximate correctness of the number 325 is shown by the 

 fact that if we assume the amount of dissociation to be little affected 

 by temperature, at any rate in the more concentrated solutions, we 



11° 18 



get «= '-j^ = ^^ . Sul)Stituting 0.0576 for « and 18.30 for 



fly which is the value for the acid of 29.83 %. we get fi^ = 318 

 (at 0"). 



"The temperature coefficient for H at 18° is about 0.0153. If this 

 is used to calculate the limiting value for the hydrogen ion at 0°, 

 the number for f*^° becomes very much lower than any of these 

 3 numbers given above, and as a coefficient is only correct in the 

 neiglibonrhood of 18° we discard this method of calculating." 



It is e\i(leiil that Hill and Shjcak have calculated fi^ at 0' for 

 H V assuming a very higii value for H''. Their value for H° at 0° 

 is about 100 units higher than the value obtained in this investi- 

 gation in the direct way. Consequently all their calculations for 

 the degree of dissociation of H F with this value for H° are not 

 reliable. 



Chemical Lahovatory, 

 Presidency College, Calcutta. 



Chemistry. — '■'Properties of elements and the periodic system" . By 

 NiLRATAN Da.-iR. (Comuiunicated by Prof. Ernst Cohen). 



In a formei- paper (Dhar Zeit. Elektro-Chem. (1913) it has been 

 shown that the heats of ionisation of elements and the temperature 

 coefficient of mobility of ions are periodic functions of their atomic 

 weights. Ill lliis paper il will be shown that some other |iro])erties 

 are also [leriodic functions of their atomic weights. 



Surface tension, capillary rise etc. 



The surface tension of liquids being an important property has 

 been investigated by various workers. There are several methods 

 of determining the value of the surface tension of liquids, the most 

 imjtorlant ones are (1) the rise in a capillary tube, (2) measurements 



