CHAPTER I. 



THE VISCOSITIES OF SOLUTIONS OF CESIUM SALTS IN MIXED SOL- 

 VENTS; THE VISCOSITIES OF BINARY MIXTURES OF THE ASSO- 

 CIATED LIQUIDS, WATER, FORMIC ACID, AND ACETIC ACID; 

 TOGETHER WITH SOME NEW FORMS OF APPARATUS. 



BY P. B. DAVIS. 



INTRODUCTION. 



We have endeavored for some time to secure enough caesium salts 

 to study their viscosities in pure and in mixed solvents, but only within 

 the past year have we been successful. Through the courtesy and 

 cooperation of Professor James Lewis Howe of Washington and Lee 

 University, a quantity of caesium sulphate was placed at our disposal. 

 This was converted first into the hydroxide, then into the carbonate, 

 and finally into the chloride and nitrate; and with these salts this 

 investigation has been carried out. 



Caesium is the most electro-positive of all the elements, and is further 

 distinguished by possessing the largest atomic volume, being followed 

 in this respect by rubidium and potassium, respectively. Since salts 

 of the latter two elements are of great interest from the viscosity stand- 

 point, it would be expected that caesium salts would possess, to a much 

 more pronounced degree, any peculiarities shown by salts of rubidium 

 and potassium. 



An examination of the literature bearing on viscosity shows that, in 

 general, only the salts of the three metals mentioned above are known 

 to lower the viscosity of water. The effect of potassium and rubidium 

 salts on the viscosities of solvents other than water, and of mixtures of 

 such solvents with one another and with water, has been the subject of 

 earlier investigations in this laboratory; and this series of investiga- 

 tions can now be regarded as partially completed by this study of 

 caesium salts in these solvents. The present investigation, therefore, 

 has been made to comprise a study of the viscosities of the two caesium 

 salts, chloride and nitrate, in water and in binary mixtures of methyl 

 alcohol, ethyl alcohol, and acetone with water. 



The results obtained with these salts of caesium in formamid as a 

 solvent are published in Chapter II, and further determinations of their 

 behavior in glycerol and glycerol-water mixtures, as well as in mixed 

 solvents containing formamid instead of water are now in progress. 



HISTORICAL. 



Jones and Lindsay, in their work on binary mixtures of the alcohols 

 with water, found that the molecular conductivities of solutions of salts 

 in these solvents were in every case less than the averages calculated 

 from the conductivities in the component solvents themselves. These 



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