Volume Changes attending Mixture, 



505 



Fig. 4. 



/ 



alcohol from left to right, it seems as though its shape would 

 be like that of the reflexion in the axis of percentages of the 

 curve of diethylamine and water (fig. 2). 



Alcohol, Bisulphide of Carbon, Amylene, Ether, Chloroform, 

 and Benzol. 



§ 267. Perhaps we may take the relationship between 

 alcohol and bisulphide of carbon as being typical of such a 

 relationship as resembles the solution of nitre in water, or of 

 fused nitre infused nitrate of sodium (§ 220) (which results 

 in expansion of the solidified alloy), or, lastly, the solubility 

 of fused nitre in water under pressure (§ 252). The method 

 of experimenting adopted reveals, however, somewhat unex- 

 pected relationships between other liquids, 

 which relationships are of a more chemical 

 character. Many chemists have of late years 

 made great use of the term " saturation," and 

 the expression has been of some real service. 

 But its unguarded use has, I venture to say, 

 given rise to some misconception. The word 

 itself certainly conveys something absolute 

 and complete; and it is undoubtedly intended 

 to convey such an idea, especially when pre- 

 fixed by " perfect " or contrasted with ' k par- 

 tial." It is only necessary to revert to the 

 types of physical saturation upon which the 

 analogies of chemical saturation are based, to 

 show that such condition is relative and not 

 absolute. Chemical saturation is not a remote 

 analogue of electric neutrality, and the latter 

 is clearly relative. 



§ 268. Two or three tubes were made, 

 similar in principle to that of fig. 3, but of 

 more general use (fig. 4). In one of these 

 the lower and upper bulbs (up to a subse- 

 quently marked point on the stem) were of 

 absolutely the same capacity (between 3 and 

 4 cub. cent.). In the second the lower bulb 

 was several times as big as the upper. By 

 adding weighed quantities of mercury to the 

 lower bulb, the ratio of contents could be 

 changed at will. 



In order to give an idea of the absolute 

 and relative dimensions, I may state that 

 in one of the tubes the exact capacity of 

 a and bf at 17°'6 was 3*3777 c. c, the total volume upon 

 Phil. Mag. S. 5. Vol. 18. No. 115. Dec. 1884. 2 L 



/^\ 



4 



CO 



