Chemistry and Physics. 65 



identical in character with the anorthosites of Essex County 

 and must be regarded as a southward extension of this rock. 

 Now, although Little Falls is nearly thirty miles from the 

 Wilmurt locality, a line connecting it with the Essex County 

 anorthosites would pass less than eight miles to the eastward 

 of Wilmurt. Thus, if, as seems probable, the anorthosite 

 of Little Falls is continuous with that of Essex County, it 

 must approach within a comparatively short distance of the 

 "Wilmurt gabbro. The possibility of establishing a connection 

 between the two rocks is thus rendered considerable, so much 

 so in fact that there can be little doubt that the gabbros of 

 Wilmurt Lake and vicinity are an offshoot of the great gabbro 

 core of the Adirondacks. 

 Hamilton College, Clinton, 1ST. T., March 1, 1894. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On a Titration method for determining Molecidar Mass. — 

 It has been shown by Nernst that, when foreign substances are 

 dissolved in a given liquid, the solubility of this liquid in another 

 with which it is partly miscible, is diminished in accordance with 

 the same laws as those which regulate the diminution of its vapor 

 pressure when the second liquid is not present. The experimental 

 confirmation of this law has been found difficult owing to the lim- 

 ited number of miscible liquids such as it requires. Kttster, how- 

 ever, has succeeded in doing this, using for the purpose a saturated 

 aqueous solution of sodium chloride on the one hand and phenol 

 on the other. If we call L and L the solubilities in water of 

 pure phenol and of phenol containing a foreign substance, g h and 

 g, the masses of phenol and of the foreign substance M z and M 3 

 their molecular masses and V and V the volumes of phenol be- 

 fore and after the addition of the foreign substance we have for 

 the value of the constant k 



h = (L-L)/L . g l IM l . M./g, . V/V . 



This value in Kiister's experiments was 1-125. 



To apply the results to the determination of molecular mass by 

 titration, Kiister uses two separating funnels, of about 100 co capa- 

 city, each containing (1) 25 cc of a saturated aqueous solution of 

 sodium chloride saturated with phenol at the temperature of the 

 laboratory, and (2) 10 co of phenol saturated with sodium chloride 

 by contact with a strong solution of this salt. Into one of these 

 funnels is now introduced a known mass of the substance whose 

 molecular mass is to be determined. It must be soluble in phenol 



Am. Jour. Sci.— Third Series, Vol. XLVIII, No. 283.— July, 1894. 

 5 



