164 Scientific Intelligence. 
cooled and weighed. Taking the liquids in pairs, the apes 
weight of either one is calculable by the formula m= ——,in 
which m, D and ¢ represent the molecular weight, the Seo : 
the boiling point and the time of evaporation respectiv Tha 
for aniline D = 0°8731 and for phenol D’ = 0°9208. In two ex- 
periments ¢ for the former was 3°8 minutes 2h t’ for the latter 3°9 
minutes. Since the molecular weight of phenol is 94, the molecular 
_ 94%0°8731K3'9 : 
weight of aniline = 0-9208K3°8. 48. Two other experi 
ments gave 91°91, the calculated value being 93. So, calculating 
the molecular weight of phenol, the values 95°57, 95°11, 95°11 
were obtained ; the calculated molecular weight being 94. Ben- 
zoyl chloride (140° 5) and ethyl benzoate (150 0) gave for the former 
the values 144°3 and 144°5; and for the latter 145°7 and 145°2. 
pondingly close results. The following are the conclusions of the 
paper: 1st, when liquids are evaporated in their own vapors, the 
times of evaporation of equal weights are inversely proportional 
to their molecular weights. 2d, the latent heats of evaporation 
are proportional nd the times of evaporation of equal weights of 
the liquids. 3d, at the boiling point, _— acetic acid has the 
molecular dvckgilit "89°8 an on formic acid, 69.— Ber. pie a 
Ges., xvii, 2199, October, 1884. 
. On the Ouantiatiée determination of Metals by Bleetrolysis. 
—In a third paper on this subject, Classen gives the results of his 
experiments on the anniv te electrolysis of metallic solutions 
by means of the magneto-electri¢ current. For this purpose he 
uses a yee all Siemens dynamo, driven from a ea a as 
‘usual. This counter-shaft however has a cone pulley and is driven 
from another counter-shaft having upon it a similar cone pulley 
and also a fast and loose pulley, over which runs the tat t Froth 
the main shaft. By this arrangement the speed of the dynamo may 
be varied at pleasure from 100 to 700 revolutions per minute. By 
means of a resistance box, placed in the main circuit, the coils of 
which vary from 6°01 to 3 ohms the current-strength may also be 
varied. So that by both these arrangements the ‘author has com 
NA webiste the gad dish containing the solution. An arm 
sliding on the same rod, but insulated from it, supports the positive 
electrode. The pe ae dish used weighs from 35 to 37 grams, 18 
9 cm. in diameter and 4°2 cm. deep and holds about 225 c.c. ia 
Care is reqs | to have it perfectly smooth and clean. For the 
determination of copper and of cadmium the double ammonium 
oxalate solution is preferred. The current used should be about 
0-02 ampére, such as would be obtained by joining we Bunsen cells 
in parallel circuit. The separation is complete a hon] ten to 
twelve hours for about 0°15 grm, copper, the end scaghtins being 
