NOTES: ON SCIENTIFIC RESEARCH. ps VA, 95 
by ice. A nscnannetee ie" a anus of 0 to 6° divided into */10° and calibrated, 
- together with a copper-wire stirrer are immersed in the test-liquid. The freezing point 
is found in the usual way. One of the following three equations serves for calculation, 
in which x = per cent. content of pure nitrobenzene in weight, t = freezing point 
| y of the water-satiirated test-liquid. 
-- < L. For the raw product washed - with water in order to get rid of acids: — 
x = 90.2 + 1.87 t. 
Il. For the raw product after Senaetion of the uncnitrated benzene by distillation 
- on water bath: —x = 890+ 2.11t.. 
SAN For distilled eirghenvete: —x = 90. 0 + 1.91 t. 
Absolutely ; pure nitrobenzene freezes at 5. 70°, and when-saturated with water at 9.22°. 
_. Simpson and Jones arrived at the above equations, in preparing, ten at a time, 
ae mixtures of pure nitrobenzene with the substances contained in raw iireben vanes 
(paraffin, carbon disulphide, benzene, m-nitrobenzene, toluene, o- nitrotoluene, p-nitro- 
toluene), and then found their freezing points after saturating with water. 
The process is . also applicable to poor-quality products, when the. sample. is 
_ mixed with a sufficient quantity of pure nitrobenzene in order to opens the freezing 
% point of the mixture above 0°. 
The evaluation of nitrobenzene by means of its. freesing point is by no means. 
-new. We have used these constants for years, and have found that the freezing point 
of a good commercial sample lies between -+- 5 and 6 : cooled to 0°, and then 
a little solid nitrobenzene is introduced. 
Ste testing of, and water- and oil- estimation in, raw Ee: see p. OF of this Report. | 
T piisiesd Notes. 
A ireatise by ic EL Durrans?) supplies a long-felt Want for a small text-book on 
distillation. He relies greatly on the work of C. v. Rechenberg 2), partly 1 in open quotations, 
partly also without acknowledging the source. Especially, the great laboriously compiled 
_ tabulated work of the boiling points corrected for normal pressures has been incorporated - 
. without mentioning whence it comes, which is all the more astonishing since the 
a2 Rechenberg, by the incorporation of a table of heats of T vaperieatin and of specific — 
preceding and succeeding table bear references to their origin. In order to keep in 
agreement with the tables the author brings a wished-for supplement side by side with 
heats of the substances coming under notice. 
In his introductory remarks, the author seeks to fid his readers of the fear of - 
the numerous formulz and graphs by saying that the art of distillation has now been 
raised to the rank of an exact science, which finds universal technical application, 
_ and, at the same time is a subject for further investigation; a happy way of describing 
the importance of his text-book on distillation: The history.of the vapour pressure 
formula, the corrections for deviations from normal pressure, also the chapter on 
constitution and boiling point, as well as Dalton’s law of partial pressures, are here 
appropriately and clearly reproduced. The author has made the great chapter on steam 
fen and fractionisation a labour of love; in it he has collected all available 
1) Perfium. Record 1 (1920), 154. — %) Theorie der Gewinnung und Trennung der <itherischen Ole durch 
Destillation. (Grundziige einer allgemeinen Destillationslehre.) 1910. = Theory of the Winning and Separation of » 
the Essential Oils by Distillation. (Outlines of a Universal Distillation-Science.) 
