90 Report of Schimmel § Co. 1921. 



0.004187 for hydrocarbons, ethers, oxides, mustard oils, thiophenols, 



sulphides, nitriles, acid 'chlorides, . 

 0.004009 „ ketones, 

 0.003946 „ esters, amines, aldehydes, 

 0.003720 „ phenols, 

 0.003574 „ acids, 

 0.003458 „ alcohols, 

 0.00301 „ hydrazones, 

 0.002835 „ quinones. 



H. Offermann 1 ) has published a method of distillation claimed to be new for the 

 estimation of the single fraction of highest value in petroleums and their residues, and 

 in general in oils which are not miscible with water, in fats, resins, tars 8jc. The 

 method is based upon the introduction of "cold" steam (100° and less) into the boiling 

 substance under distillation. The author believes that he can dispense with a vacuum 

 in the cautious distillation of sensitive substances. Since we cannot distil, however, 

 by the aid of liquid water, even when it is introduced in the shape of drops, the heat 

 which the distillation necessitates must externally be applied. In the most favourable 

 case, therefore, this method would be the well-known water distillation, the sparing 

 character of which has long been understood. A new idea can certainly not be 

 discovered in the utilisation of saturated steam. 



In the course of a research on the substance, in crude acrolein, which stabilises 

 acraldehyde Ch. Moureu, Ch. Dufraisse and P. Robin 2 ) have made use of the method 

 of repeated fractionated distillations at exactly the same pressure, uniting always such 

 fractions with one another which were equal, not only as to boiling point, but also 

 as to density and refractive index, and submitting these again to fractionation. It may 

 expressly be stated for the reader not acquainted with the principles of the theory of vapour 

 pressures 3 ), that this method will yield not only uniform substances in pure condition, 

 but also mixtures in definite proportions of substances of two or more constituents. 



When the distillation is conducted at reduced pressure, this pressure has to be 

 kept constant throughout. In the opinion of the authors this is better secured by 

 means of their differential manometer of vaseline oil, which they illustrate in their 

 paper, than by the aid of a mercury manometer. The former manometer is said to 

 be 15 times more accurate and sensitive than the ordinary vapour-pressure gauges. 



H. C. Wood Jr. 4 ) has determined the solubility of some essential oils in mixtures of 

 alcohol and water. The method of which he makes use resembles in principle that 

 recommended by Dowzard 5 ) (addition of water to a concentrated solution of the oil 

 in 93 per cent, alcohol to incipient turbidity). Wood himself admits that this method, 

 which so far has only rarely been applied, is subject to errors. 



None of the oils examined by the author gave a clear solution with 100 parts of 

 55 per cent, alcohol. At a certain point, however, the solubility of the oil decreased 

 markedly with slight changes in the concentration. This "critical point" of Wood was 

 near 60 per cent, for clove oil, and near 90 per cent, for peppermint oil 6 ). In general 

 most of the essential oils were not readily-soluble in 70 per cent, alcohol. 





!) Chem. Ztg. 44 (1920), 773. — 2 ) Compt. rend. 169 (1919), 1068; Bull. Soc. chim. IV. 27 (1920), 523. — 

 3 ) Ostwald, Lehrbitch der allgemeinen Chemie, 2 nd ed., vol. II, 2: Venvandtschaftslehre, zweiter Teil, p. 992; 

 v. Rechenberg, Gewinnung und Trennung der dtherischen Ole, p. 572. — 4 ) Journ. Amerie. pharm. -Assoc. 9 

 (1920), 878. — 5 ) Cf. Gildemeister and Hoffmann, The Volatile Oils, 2 nd ed., vol. I, p. 568. — e ) Further 

 information as to the interpretation of these figures is not given. 



