276 Prof. J. G. MacGregor on the Calculation of 



the value of the variation of temperature, if the carbonic acid 

 decreases to 0*67 or increases to 1*5 times the present -quan- 

 tity. In the first column is printed the latitude; in the second 

 and third the nebulosity over the continent and over the 

 ocean; in the fourth the extension of the continent in hun- 

 dredths of the whole area. After this comes, in the fifth and 

 sixth columns, the reduction factor with which the figures- in 

 the table are to be multiplied for getting the true variation of 

 temperature over continents and over oceans, and, in the 

 seventh column, the mean of both these correction factors. 

 In the eighth and ninth columns the temperature variations 

 for K = 0'67, and in the tenth and eleventh the corre- 

 sponding values for K = l*5 are tabulated. ; 

 The mean value of the reduction factor N. of equator is for 

 the continent (to 70° N; lat.) 1-098 and for the ocean 0*927, in 

 mean 0*996. For the southern hemisphere (to 60° S. lat.) it 

 is found to be for the continent 1*095, for the ocean 0'871, in 

 mean 0*907. The influence in the southern hemisphere will, 

 therefore, be about 9 per cent, less than in the northern. 

 In consequence of the minimum of nebulosity between 20° 

 and 30° latitude in both hemispheres, the maximum effect 

 of the variation of carbonic acid is displaced towards the 

 equator, so that it falls at about 25° latitude in the two cases 

 of K = 0-67 and K= 1-5. 



XXXII. On the Calculation of the Conductivity of Mixtures of 

 Electrolytes. By Prof. J. G. MacGkegok, Balhousie 



College, Halifax, N.S.* 



ARREENIUS has deduced f, as one of the consequences 

 of the dissociation theory of electrolytic conduction, 

 that the condition which must be fulfilled in order that two 

 aqueous solutions of single electrolytes, which have one ion 

 in common and which undergo no change of volume on being- 

 mixed, may be isohydric, i. e. may on being mixed undergo 

 no change in their state of dissociation or ionisation, is that 

 the concentration of ions, i. e. the number of dissociated 

 gramme-molecules per unit of volume, shall be the same for 

 both solutions. He obtained this result by combining the 

 equations of kinetic equilibrium for the constituent electrolytes 

 before and after mixture. 



According to the above theory, the specific conductivity 

 of a mixture of two solutions of electrolytes 1 and 2, whose 



* Abstract of a paper read "before tlie Nova Scotian Institute of Science 

 on the 9th of December, ] 895. Communicated by the Author, 

 f Zschr.f. physikalische Chemie, ii. p. 284 (1888). 



