122 REPORT OF SCHIMMEL & Co. APRIL 1914. 
by Messinger and Vortmann"*), with this exception, that sodium bicarbonate is employed 
in the place of soda liquor. The authors found that very accurate results were obtained 
by proceeding as follows: about 50 cc. of n-sodium bicarbonate solution is placed in 
a glass-stoppered bottle of 1/2 litre capacity and diluted with 100 cc. water. To this 
is added from a burette 15 cc. of a solution containing as much of the phenol under 
examination as corresponds to, say, a decinormal solution. To this added */s0-normal 
iodine solution in excess, until a permanent brown colour is obtained. The excess 
of iodine should amount to 20 p.c. The mixture is now vigorously shaken for one 
minute, diluted with 50 cc. of 2-n-sulphuric acid, and the excess of iodine titrated 
back with decinormal thiosulphate solution, 5 cc. of a 20 p.c. potassium iodide solution 
being added. Starch is used as an indicator. The experimental temperature should 
be from 20 to 25°. Of the solutions, the n-sodium bicarbonate solution and the 
2-n-sulphuric acid need only agree approximately. 
In order that the reaction may proceed rapidly it is important to shake the aanteune 
thoroughly after adding the iodine-solution. When this is done the iodine-compound 
is formed completely within one minute. With thymol it affords thymol di-iodide. In 
order to make sure that any iodine which may have entered into the hydroxyl-group 
is again liberated, care should be taken that a little hydriodic acid is always present; 
hence the addition of the potassium iodide solution before the excess of iodine is 
titrated back with thiosulphate. Titration can only be regarded as completed when 
the blue colouration does not return even after a lapse of 10 minutes. ° 
Physical Notes. 
E. Hildt?) describes a fractionating apparatus devised by E. Chenard, in which the 
force exerted by the ascending steam for overcoming the exterior pressure is used for 
effecting partial recondensation. Between the still and the condenser which communi- 
cates with the outer air, a tube is to be placed in which the heat is perfectly isolated and 
in which therefore no condensation caused by cooling from without can take place. 
Notwithstanding this, partial condensation of steam is said to occur within the tube, 
this condensation being determined entirely adiabatically by the exterior action of 
the steam alone. This proposal is open to criticism, firstly that the resistance of 
the intermediary piece, (which, judging from the figure accompanying the description, 
consists of a quite narrow, long, spirally-beat glass-tube, fitted with parts for carrying 
off the condensate) in respect of the steam passing through it corresponds to a dimin- 
ution in pressure which increases in proportion to the narrowness of the diameter of 
the tube and the rate of velocity at which the distillation proceeds. In the case under 
review both these conditions obviously apply. The occurrence of these conditions is 
known. In the second place it remains doubtful whether the shape of the splash-head 
as shown in the illustration admits of even an approximately adiabatic action; on the 
contrary, it would seem that a quite considerable degree of exterior cooling (attended 
by so-called “wild dephlegmation”) is to be expected. Thirdly, there can be no 
question of any real duty against the atmosphere so far asthe stationary process of 
conducting the steam from the still to the condenser is concerned, but only so far as 
regards the initial fractions at the commencement of the distillation. 
SS 
j 
/ 
1) Berl. Berichte 28 (1890), 2753. Also comp. Gildemeister and Hoffmann, The Volatile Oils, 294 Ed. 
Vol. I. p. 594. — *%) Bull. Soc. chim. IV. 15 (1914), 37. 
