334 Messrs. Dupre and Page on the Physical Properties [Mar. 11, 



introduced, and the mouth of the flask closed by a doubly perforated cork. 

 Into one of these perforations a thermometer was introduced, into the 

 other a bent tube, dipping beneath the surface of the liquid in the flask, 

 and connected at its other extremity with a Liebig condenser. This tube 

 had a lateral opening (inside the flask) just beneath the cork ; by means of 

 this the vapour escaped to the condenser, and trickled back into the flask 

 after being condensed. Thus the composition of the mixture was retained 

 as uniform as possible. Thus estimated, the barometer standing at 744*4 

 millims., the boiiing-points are given in the following Table. 



Percentage of 



Boiling-point 



Boiling-point 

 calculated*. 



Difference. 



alcohol, by weight. 



observed. 



o 



99'4 











— 6-27 



IO 



90-98 



97-25 



20 



86-50 



95-10 



-8-6o 



30 



84-01 



92-95 



-8-94 



40 



82-52 



90-90 



-8-38 



45 



8r 99 



89-72 



-7'73 



5o 



8i'33 



88-6o 



-7-27 



60 



80-47 



86-50 



— 6-03 



70 



79-61 



84-35 

 82-20 



-4-74 

 -3-36 



80 



78-84 



90 



78-01 



80*05 



— 2-04 



100 



77-89 











Section 4. Capillary Attraction. 



This was estimated by carefully observing the heights to which the 

 several mixtures rose in a capillary tube 0'584 millim. in diameter. 



These heights were measured by means of a telescope and a millimetre- 

 scale etched on a glass rod. This glass rod was fixed to the capillary tube, 

 and terminated at its lower extremity in a point, which was made just to 

 touch the surface of the liquid. 



Several precautions were necessary to render the measurements accurate. 



The results are contained in the following Table : — 



Percentage 

 of alcohol, by 

 weight. 



Height, assuming 

 water 

 = 100 inilliras. 



Relative molecular 

 attraction. 



Height calculated. 



Difference. 







IOO'OO 



IOO'OO 



IOO'OO 





10 



69-17 



68-07 



93-n 



-25-04 



20 



56-43 



54-83 



86-22 



— 3 J -39 



3° 



48-19 



46-15 



79-34 



-33-I9 



40 



45-30 



42-56 



72-45 



-29-89 



45 



43*74 



40-64 



69-00 



-28-36 



50 



4^93 



39-43 



65-56 



—26-13 



60 



42-30 



37-89 



58-68 



-20-79 



70 



41-76 



36-42 



S r 79 



-i5'37 



80 



41-29 



35-o3 1 



44-90 



- 9-87 



90 



40-54 



33-35 



38-02 



- 4'67 



100 



39-21 



3i'i3 



3i-i3 





The third column gives the length of a column of water equal in weight 



* Calculated on the assumption that the alcohol and water in a mixture have an 

 influence on the boiling-point of the mixture proportional to their respective weights. 



