DEPRESSIONS FOR ELECTROLYTES MACGREGOR. 227 



coincides with the lower part, but in the upper part diverges to 

 the left. In form the curve is thus probably trustworthy. But 

 being plotted with Barnes' coefficients it may be too high or too 

 low. The R W and J W curves (see inset) are not open to 

 this suspicion, but at the dilutions to which even.their lower and 

 more trustworthy parts apply, they may have begun to diverge 

 unduly rightwards. If the L B B curve (see inset) be raised 

 about 2.5 per cent., as is shown to be necessary by a comparison 

 of Whetham's and Barnes' coefficients, it comes into a position 

 to the left of the R W and J W curves, the usual relative 

 position of the curves of these observers. Loomis's own curve 

 for somewhat greater dilutions than those of the L B B curve, 

 when plotted with Whetham's coefficients, coincides very nearly 

 with the boundary line of the inset ; Wildermann's is a little to 

 the left of Loomis's, and somewhat steeper. Both exhibit a 

 slight rightward bending, as do all the others. 



It would be difficult to draw a mean curve with any confi- 

 dence ; but any such curve would run about midway between the 

 1 2 and 2 4 (1.83) lines, would have a slight rightward bending 

 at its upper end, and if produced with diminishing curvature, 

 would run out to a point a little to the right of the 1 2 (1.85) 

 intersection. 



If this intersection were the starting point of the curve, and 

 if there were no association, the curve should lie wholly to the 

 right of the 1 2 (1.85) line. If, as dilution diminished, 

 sufficient doubling of molecules with unchanged mode of ioniza- 

 tion should occur, the curve, after first bending away from that 

 line to the right, would change its curvature, bend towards the 

 line.and cross it, and then run towards, and finally away from, the 

 2 4 line, as the mean curve appears to do. 



As the 2 2 line is far to the left, the mean curve might be 

 accounted for also, on the assumption of a very slight formation 

 of double molecules dissociating into two ions ; and a slight 

 formation of such molecules would probably involve no greater 

 variation of the migration numbers with concentration than 

 has been observed. 



