34:0 6^ E. Lmebarger— Viscosity of Mixtures of Liquids, 



(f. II.) Five pounds of commercial acetic ether were dried 

 over fused calcium chloride for a few days ; and after filtra- 

 tion from this salt were made to stand over phosphoric anhy- 

 dride for some time. The ether was then distilled, the distil- 

 late bein^ collected in two portions, one of which boiled at 

 71°-0-71°-3 (uncorr.), the other at 7I°-3-71°-4 (uncorr.) Each 

 of these distillates was again distilled over phosphoric anhy- 

 dride, and both were found to boil at identical temperatures. 

 The specific gravity of one sample at 25°'0 referred to water 

 at the same temperature was determined to be 0-89155 ; that 

 of the other under similar conditions, 0'89157. 



lY. Discussion of Results, 



The data in the preceding section are seen to be in corrobo- 

 ration of Wijkander's (loc. cit.) results; in no instance does a 

 maximum of viscosity appear. The observed viscosities are all 

 less than those calculated by the rule of mixtures, except in 

 certain mixtures of benzene and chloroform (Table YII) and 

 of benzene and carbon bisulphide (Table III) ; in these mix- 

 tures, however, the differences are less than those detectible by 

 the apparatus, so that they cannot be really counted as excep- 

 tional. 



With mixtures of certain liquids, as of benzene and toluene 

 (Table II), benzene and carbon bisulphide (Table III), benzene 

 and chloroform (Table YII), toluene and carbon bisulphide 

 (Table X, ether and carbon bisulphide (Table XII) and acetic 

 ether and carbon bisulphide (Table XYI) the differences are so 

 slight that they may be due principally to experimental errors, 

 and, consequently, these liquids may be said to preserve their 

 viscosities without appreciable change in mixture. In other 

 mixtures, on the contrary, considerable differences between the 

 theoretical and found values of the viscosities present them- 

 selves, the greatest differences occurring when about equal 

 proportions of the liquids are mixed. 



The greater the differences between the viscosities of the 

 pure liquids, the greater is found to be the differences between 

 the calculated and observed values of the viscosities of their 

 mixtures. This is easily seen in the mixtures of benzene, 

 whose viscosity is 0*00599, and nitrobenzene, whose viscosity is 

 0-01834, differences amounting to 0-00372 being found (Table 

 YI); also, in mixtures of toluene (viscosity = 0-01954), where 

 the differences, found and calculated, are as large as 0*00345. 



Yet, even when the viscosities of the pure liquids are nearly 

 the same, the differences between the theoretical and observed 

 values of the viscosities of their mixtures is not inconsiderable ; 

 thus the mixtures of acetic ether (viscosity — 0*00577) and 

 ethyl iodide (viscosity = 0-00462) there are differences of as 

 much as 0*00144. 



