PHYSICAL CHAEACTEES OF MIXTUEES AND SOLUTIONS. 
337 
Table IV. 
Per cent., by weight, of 
absolute methylic 
alcohol. 
Boiling-point 
observed. 
Boiling-point 
calculated. 
Difference. 
0 
99-93 
10 
82-57 
95-80 
1 3-23 
20 
75-26 
91-76 
16-56 
30 
70-68 
87*53 
16-85 
40 
68-31 
83-40 
15-09 
50 
67-08 
79-26 
11-18 
60 
65-75 
75-13 
9-38 
70 
64-65 
71-00 
6-35 
80 
63-13 
66-87 
3-74 
90 
100 
60-96 
58-60 
62-73 
1-77 
Section IV . — Capillary Attraction. 
The capillary attraction is estimated as follows : — A somewhat wide glass cylinder, 
the rim of which is accurately ground, stands on a metal frame with three levelling- 
screws, by means of which the rim of the cylinder can be placed perfectly horizontal. 
On the rim rests a stout metal bar, through which are drilled three holes exactly at right 
angles to the lower face of the bar, so that a tube or screw fitting into one of these 
holes will stand vertical when the rim of the cylinder is horizontal. Two of these holes 
carry capillary tubes ; in the third a long fine screw, pointed at both ends, can be screwed 
up and down. A mark is etched on each capillary tube, and by depressing or raising 
the tube the liquid under examination is always made to rise exactly to this mark ; the 
influence of any irregularity in the bore of the tube is thus avoided. The experiment 
is conducted as follows — The perfectly clean capillary tubes are put into their respective 
holes in the plate, and this is placed on the levelled rim of the cylinder. The mixture 
to be examined is poured into the glass, and a small quantity of the liquid is sucked 
through each of the tubes by means of a suction-tube. The height of the tubes is then 
adjusted so that the lower part of the menisci just touches the marked point of the 
tubes. The screw is now carefully screwed down until the point just touches the surface 
of the liquid in the cylinder ; this contact can be made with the utmost nicety. It now 
only remains to determine the vertical distance between the upper point of the screw 
and the lowest part of the two menisci in the tubes, when, the total length of the screw 
being known, the elevation of the liquid in the capillary tubes becomes known. The 
vertical distances are measured by means of a very excellent cathetometer, which allows 
the reading of 0-025 millim. 
Table V. gives the results obtained. 
Column 1 gives the percentage of methylic alcohol by weight. 
Columns 2 and 3 give the observed heights of the threads in millims. 
Columns 4 and 5 give the heights supposing water stood at 100 millims. 
Column 6 gives the mean of columns 4 and 5. 
Column 7 gives the length of a column of water equal in weight to the thread of 
