20 Report of Schimmel 8* Co. 1921. 



we could write years ago on the strength of personal observations and enquiries con- 

 cerning the production of different sorts of lemon oil 1 ). According to that firm, the 

 citral content would be 4 per cent, for Acireale and Giarre oil, about 5 per cent, for 

 Messina oil and 3.5 to 4 per cent, for Barcelona oil. Their figures for the optical rotation, 

 which is particularly characteristic for the different kinds of oil, are:— oil coming from 

 the district between Acireale and Giarre «-|-59 to +60°, oil from Giardini a + 62 to 

 + 63°, and oil from Messina « + 57 to +59°. 



Lemon oil has recently been prepared also by the following method 2 ) which differs 

 from the previously used "spugna" and machine methods. The lemons are turned between 

 two surfaces, the one concave, the other convex, which are set with small pins to scrape 

 the skin of the fruit and to tear the oil-cells. A jet of water passes over the fruit and 

 carries with it the products which have been liberated from the cells. This water is 

 collected in suitable vessels; after a while the main bulk of the lemon oil will settle, 

 clear for easy recovery, while the turbid portion of the liquid is purified by filtration. 



Compared to the old spugna process the method seems to be inferior in so far as, 

 according to P. Leone 3 ), the treatment with water impairs the quality of the oil. Leone 

 proved in the first instance that, in oils which he had shaken with 6, 20 and 40 times 

 the amount of water, the specific rotation was constantly increasing whilst the density 

 and the citral contents correspondingly diminished. The constants of the oil were very 

 little affected, however, when the oil was shaken with water which had already been 

 saturated with lemon oil. 



The influence upon the quality of the oil of the water treatment can best be seen 

 from the following table in which the constants of the oils, as prepared by the different 

 methods from the same material, are reproduced. 



Lemon oil Citral Evaporation 



prepared by di.50 rt D2oo content*) residue 



spugna process . . 0.8583 +60° 20' 4.25 per cent. 2.90 per cent, 

 water treatment . . 0.8576 +60° 32' 3.90 per cent. 2.95 per cent. 

 Leone recommends to make use, in the new method, only of water already saturated 

 with lemon oil, since the quality of the product would then little be affected. 



A. Guido 5 ) has continued his research on the demonstration of adulterations in 

 lemon oil. In the manner previously described ) he investigated the influence of alcohol 

 of different concentrations upon the critical solution temperature. This temperature rises 

 with increasing density of the alcohol, and with adulterated lemon oil to a greater extent 

 than with the genuine oil. Especially with the higher fractions of his two samples of 

 oil he observed a great difference between the two temperatures when using an alcohol 

 of the highest suitable water contents. Guido therefore assumes that the application of a 

 suitable alcohol (the constants of which were, in one case quoted by author, di 5 o 0.8436, 

 87.11 percent, by vol.) would further improve the sensitiveness of this method. 



In a further research Guido 7 ) deals with the determination of the citral in lemon oil 

 and in its fractions (by the method of Kleber) after treatment with solution of sodium 

 bisulphite ( 1 00 grams of sodium bisulphite, 36 grams of sodium bicarbonate and 1 000 grams 



] ) Cf. Report April 1896, 30; November 1908, 62. Cf. also Chace, The by-products of the lemon in Italy, 

 Report April 1910, 64. — 2 ) Sulla essenza di limone estratta in presenza d'aqua. Estratto dal Giornale 

 di Chimica Industriale ed Applicata. November 1920. Reprint kindly sent to us. — 3 ) Ibidem. — 4 ) Method 

 of determination not stated. — B ) Sulle essenze di limone. Estr. Anncdi R. Stazione di Agricoltura e Frutticoltum 

 Vol. V. 1919, p. 1. As per a reprint kindly sent us. — 6 ) Cf. Report 1920, 31. — 7 ) Distillazione frazionata 

 e compitsiti carbonilici. hoc. cit. p. 8. 



