Volume 6

Technical methods of chemical analysis / edited by George Lunge ... in collaboration with E. Adam, F. Barnstein [and others] ... English translation from the latest German ed., adapted to English conditions of manufacture, edited by Charles Alexander Keane ... in collaboration with T.L. Bailey, C.O. Bannister [and others].

  • Lunge, Georg, 1839-1923.
Date:
1908-1914
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Technical methods of chemical analysis / edited by George Lunge ... in collaboration with E. Adam, F. Barnstein [and others] ... English translation from the latest German ed., adapted to English conditions of manufacture, edited by Charles Alexander Keane ... in collaboration with T.L. Bailey, C.O. Bannister [and others]. Source: Wellcome Collection.

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    hot aqueous digestion method, Kiehle’s grinding machine was em- ployed with most satisfactory results (A. R. Ling). Beetroot slices may be reduced to a similar finely divided pulp by means of the crushing machine also constructed by Kiehle.1 A satis- factory pulp may also be obtained both from beetroot and beetroot slices by means of the special contrivances of Herles2 and of Pellet.5 From whole beetroots a coarser but uniformly ground pulp, which is quite suitable for most purposes, may be obtained by means of hand o-raters whilst meat-mincing machines, which have been much improved recently may be employed for slices. Finally, the boring machines constructed by Dehne of Halberstadt* and by M. Wahrendorf of Oschersleben, should be mentioned. These machines, even when worked by hand, give a very uniform pulp without any loss of juice. All these machines must be kept clean and in good working order. Prior to analysis, the pulp (preferably about I kg.) is carefully mixed and placed in a covered vessel. Owing to its tendency to ferment, and the readiness with which it loses water, the quantities o pulp required for each determination must be weighed out successively as quickly as possible, and the vessel must be covered again direct y a portion has been removed. According to Pellet,5 however,the PulP may be kept unchanged for three to five hours, without addition of any preservative, in well - stoppered vessels at the ordinary temperature. A.—Estimation of Sucrose. In accordance with the method published by the International Commission for Standard Methods of Sugar Analysis m 1900, the amount of substance to be weighed out for the determination of sucrose is 26 g. This quantity is the “ normal weight” for the Soleil-Ventzke- Scheibler polarimeter, the scale of which is generally used (excepting in France), and its employment is taken for granted in the various modified, half-shadow polarimeters designed by Schmidt and Haensch hence, the above-mentioned International method of 1900 will, in future, 1 Z. Ver. dent. Zuckerind., 1892, 42, 281 ; this machine causes a slight loss of juice and heating of the pulp. 2 Z. Zuckerind. Biihm., 1900, 25, 209 ; 1901, 20, it>7- _ „ s p •, .. 3 Sucrerie indigene, 1903, 62, 644 J this instrument is designated Sans P . 4 Zentralbl. fur die Zuckerindustrie der Welt, 1897, p. 05. b Bull. Assoc. Chim. Suer., 1905, 23, 539- , e Z. Ver. dent. Zuckerind., 1900, 50, 357 5 ^V^JiThe intrust Concerning the control 7 Precise directions for use are always supplied with are caused by the of the instrument with normal quartz plates and temperature) cf. Herzfeld, Z. Ver. compression of these plates (and consequently ° gg and igo0, p. 902 ;/. Chem. !nd., deut. Zuckerind., 1899, 49, I, and F. lecimann,» •>]?• j d manipulation of the polari- .900, .9. .0.7. Concerning ih, ^ p. 448. meter, their detection and elimination, cf. Kovar, uesie, g