PHYSICAL CHARACTERS OE MIXTURES OE ALCOHOL AND WATER. 
611 
Without entering into any theoretical speculations, sufficient data for which they do 
not at present possess, the authors would point out certain relations, more or less inti- 
mate, which connect the various physical properties of mixtures of alcohol and water, 
and which have been brought out by the above series of experiments. 
It will be seen by a glance at Plate LXI V. that, with one exception ( i . e. expansion of 
17 to 18 per cent, spirit), the numbers found never coincide with those calculated, as 
explained in the foregoing paper; in fact all the characters examined fall naturally 
into two classes — I. containing those which, at an alcoholic strength of 30 per cent, 
by weight, reach a maximum deviation from the number calculated, and II. those 
which reach a maximum deviation at 40 per cent. Each of these classes may be divided 
into two subclasses — one containing those properties in which the numbers found are 
above those calculated, and a second containing those in which they are below. 
Class I. 
a. Specific heat. 
Heat produced by mixing. 
b. Boiling-points. 
Capillary attraction. 
Class II. 
c. Rate of expansion. 
d. Compressibility. 
On examining these in detail some remarkable facts will be noticed. In subclass a, 
Specific Heat, it will be seen, by Table VII. and Plate LXIV., that the first addition of 
alcohol to water, though alcohol has a specific heat much less than that of water, 
actually raises the specific heat ; so that a mixture between 30 per cent, and 40 per 
cent, has the same specific heat as water. 
On comparing the elevation of specific heats found, above the theoretical specific 
heats calculated as above, with the amount of heat produced by mixing, it will be seen 
(Plate LXIV.) that mixtures producing the same amount of heat possess the same elevation 
of specific heat ; and further, if the number of units of heat produced in the formation 
of any mixture be divided by 3‘411 in each case, a number is obtained which expresses 
the elevation of the specific heat of such mixture above its theoretical specific heat. 
By thus calculating the specific heat from the units of heat evolved, or vice versa, 
numbers are obtained which agree so closely with the numbers found, that the difference 
is quite within the limits of experimental error ( vide Table XIV.). 
