Volume Changes attending Mixture* 509 



it takes place. But I believe I am right in assuming that 

 this effect would not in this instance materially shift the place 

 of the maximum, although it would alter every one of the 

 individual numbers, and that not in the same proportion. 



The curve, fig. 5, shows the relationship of increased heat- 

 tension to the proportions of chloroform and ether by weight 

 by which it is caused. 



From these six experiments, therefore, we find that the 

 greatest change (rise) of temperature takes place when the 

 liquids are in the proportion of 1 ether to 1*615 of chloroform 

 by weight, which is the proportion of C 4 H l0 O to CHC1 3 . 



§ 271. This method of experimentation, however, does not 

 allow of such great accuracy as the method of change of 

 volume. If it be found that the greatest change of volume 

 takes place when these weight-ratios (1 ether to 1*615 of chlo- 

 roform) are mixed, and that a very small change of ratio 

 either way diminishes the change of volume, this evidence 

 will be much strengthened towards the conclusion that the 

 relationship is indeed between molecule and molecule. 



Taking, therefore, the tube like A (fig. 3), having equal 

 bulbs of 3*2325 c. c, I put 9*304 grams of mercury into the 

 lower bulb. This reduced the capacity of the lower bulb 

 0*693 c. c, bringing it to 2*5390, the upper bulb by 3*2325. 

 They are in the ratio of 1*380 to 1*084, which, again, are in 

 the ratio of the molecular volumes (molecular weights divided 

 by specific gravities) of the two liquids. The ratio-value of the 

 capacity of the calibrated capillary-stem has now, of course, 

 to be taken upon a lesser total volume — namely, upon 5*7715 

 instead of upon 6*4650. The first quantities of chloroform 

 added should be shaken and warmed with the mercury, so as 

 to displace the film of air between the mercury and the glass, 

 or some dissolved gas. If this is not done before the ether is 

 added, air-bubbles arise when the two are mixed, and vitiate 

 the readings. 



The result for equimolecular volume at 17° # 6 is 0*0116756: 

 chloroform 1, ether 1*2731. 



Instead of 9*304, I now introduced only 9*0 grams of mer- 

 cury ; this reduced the lower bulb 2*5699 c. c, and the two 

 together to 5*8024; the volume-ratio between the two being 

 1 chloroform to 1*258 ether. The shrinkage on the new 

 volume was 0*0114783. 



Next I introduced 9*6 grams of mercury. This reduced 

 the lower bulb to 2*5241 c. c, and the two together to 5*7566. 

 The volume-ratio between the two is now 1 chloroform to 

 1*2806 ether. The shrinkage on the new volume was 

 0*015706. 



