C. E. Linebarger — Viscosity of Mixtures of Liquids. 33B 



of abscissas and viscosities on the axis of ordinates for mix- 

 tures of water with some of the alcohols of the fattj series, 

 and include the data communicated bj Pagliani and Battelli. 

 An inspection of them shows that the most considerable maxi- 

 mum of viscosity is present at the lowest temperature, and 

 that, as the temperature rises, the maximum becomes less and 

 less pronounced. The determinations were not made at temper- 

 atures above 60°, but even at this temperature the maximum 

 has in most cases nearly disappeared. But it is known that at 

 60° the association of the molecules of water and the lower 

 alcohols is still not inconsiderable, so that it is perhaps permis- 

 sible to assume that at higher temperatures the maximum of 

 viscosity may disappear entirely. 



The curves also show that the position of the maximum with 

 respect to the axis of abscissas varies in a regular way, so that 

 it is not allowable to conclude that there is any detinite relation 

 between the maximum of viscosity and chemical composition, 

 that is, the interpretation of these data in favor of the hypothe- 

 sis that the maximum marks the existence of a "hydrate" is 

 untrustworthy. 



E'ow, the only data we possess on the internal friction of 

 mixtures of normal liquids are to be found in Wijkander's 

 paper (loc. cit.) and these are not very numerous or accessible. 

 The object of this paper is the determination of this physical 

 constant for a number of mixtures of normal liquids. 



II. Method of Determination of Viscosity. 



The apparatus used in the determinations of the internal 

 frictions of the liquids and their mixtures was that devised by 

 Ostwald.* Two such instruments were used, one emptying 

 itself of pure water at 25°'0 in 105'6 seconds, the other in 

 203*5 seconds. One or the other was taken so as to make the 

 time of transpiration at least more than 100 seconds. The 

 time was taken by means of a chronometer to within a few 

 tenths of a second. Never less than three and generally from 

 five to ten determinations were made for each mixture, and 

 their average set down as the true time of transpiration. The 

 apparatus was kept in all determinations at the temperature of 

 25°'0 by immersing it in several quarts of water of that tem- 

 perature contained in a large jar of clear glass. As the coef- 

 ficient of internal friction varies considerably with the tem- 

 perature, great care was taken to keep the temperature uniform, 

 and it is believed that during an experiment it did not vary 

 more than =b 0°-02. The thermometer used was graduated in 

 tenths of degrees and permitted the estimation of a fiftieth of 



* Lehrbuch der allgemeinen Chemie, i, 550, 1889. 



