Tensions of Liquids and their Chemical Constitution. 89 



be somewhat variable, since the first drop was evidently 

 smaller than the succeeding ones. Not so much confidence, 

 then, is to be placed in the results obtained by the dropping of 

 heavier liquids through lighter, as of lighter up through 

 heavier ones, since in the latter case no such phenomena were 

 observed. 



In the dropping of the liquids, besides the main drop, a 

 much smaller secondary drop would also form almost invari- 

 ably. In general, the larger the main drops,. the smaller the 

 secondary drops, so that but a slight error is introduced in neg- 

 lecting the latter, when the former are comparatively large. 

 The formation of these secondary drops may be explained as 

 follows : The main drop, just before breaking loose, is con- 

 nected to the mass of the liquid by a short cylinder, the cir- 

 cumference of which is that of the orifice of the pipette. 

 When the large drop tears itself from the connecting cylinder, 

 a certain impulse or shock is communicated to the latter, so 

 that it is severed from the mass of liquid, and under the action 

 of superficial tension and gravitation assumes a spheroidal 

 form, appearing as a drop. In this paper, I have not attempted 

 to make any corrections for these secondary drops, although, 

 without doubt, their appearance is intimately connected with 

 the superficial tension of the liquid in question. 



When water was dropped down through other liquids, it 

 would run up around the orifice of the pipette so that the 

 drops were larger than they should be, and consequently the 

 results were quite variable. This was prevented by the fol- 

 lowing simple device. A test tube just small enough to enter 

 the outer vessel of the dropping apparatus was cut off so as to 

 form a tube open at both ends about two inches long. In one 

 end was fitted a cork through which a hole was pierced so that 

 the stem of the pipette could be thrust through it. In the 

 other end was set a thin ring of cork made by cutting a cross- 

 section of a good soft cork and filing it out. This ring was 

 cut into four times so as to form four shallow clefts situated 

 90° apart. In these clefts were inserted fine-spun threads of 

 glass, so that they crossed at the center of the ring. The 

 orifice of the pipette was shoved down close enough to the inter- 

 section of the glass threads that a drop, when nearly half formed 

 would touch it. The drop then, instead of running up the 

 sides of the pipette would be confined to the orifice, the 

 crossed threads serving as a support for the drop during its 

 formation. With this little device, the determinations were 

 entirely concordant. 



We will first take up the discussion of the results obtained 

 with liquids lighter than water. These were all hydrocarbons 

 of the benzene series from the establishment of Kahlbaum 



