JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The above general scheme for costing .should present no serious difficulty in a small or medium-sized factory. Some trouble and expense would be involved in starting up and running it, but once it is organised it should be a valuable asset. Where such a scheme is too involved or where the produc- tion, filling and dispatch departments are intermixed, it should be an easy matter to pick on the essentials of use and to operate a simpler scheme covering these points only. ON PURGHASING ESSENTIAL OILS W. R. LITTLE JOHN, B.Sc., A.R.I.C.* With the widening appeal of odours and flayours many not previously interested in Essential Offs have now to purchase them. Guidance is given to the accepted works of reference for the chemical analysis of samples and practical suggestions are made for their olfactory and/or gustatory evaluation. The attitude of the industry towards variation within deliveries is explained. THE •UYING and evaluation of essential oils is the concern of nearly all who have to impart aroma and flavour to a product. The ramifications of the essential oil industry are large, and it often falls to the lot of a buyer or a chemist in another branch of chemistIy quite different from that of essential oils to have to buy and pass judgment on various samples of essential oils from different sources. The offers from different sources vary tremendously in price, and this has to be taken into account in conjunction with the quality when the final decision has to be made. It cannot be too strongly stressed that a chemical examination to see if the essential oil fulfils certain standards set out in the literature is in reality only part of the evaluation procedure. Another point to be noted is that essential oils are natural products and as such vary from season to season and from locality to locality. In some respects they may be likened to wine for vintage years and localities. The one salient point that must be borne in mind by the buyer and by the chemist analysing the oil is that it is bought in order to perfume or flavour a finished product, and it is the odour or flavour of the finished product which is the deciding issue since these are the selling factors of the product. So one test which must be carried out before any final decision can be made is to make a small batch of the finished product and to compare this with a standard one to see how the flavour or the odour of the essential oil comes through. * Perfumery and Essential Record, Diana House, 33-34, Chiswell Street, London, E.C. 1. 260

ON PURCHASING ESSENTIAL OILS A chemical examination is, of course, a necessity, but it should be looked upon rather as a diagnosis rather than a final verdict. To a chemist unaccus- tomed to evaluating these products there are special peculiarities he will find that are a little removed from ordinary routine analysis. There are several reference books which give details of the special methods employed in this field, and one may name amongst others Guenther, "The Essential Oils," Volume I Simon-Thomas, "Laboratoriumsbuch fiir die Industrie der Riechstoffe, 4-5 Auflage" British Standard No. 2073: 1953, "Methods of Testing Essential Oils," "Methodes et Constantes Analytiques des Huiles Essentielles," issued by the Syndicat National des Fabrica•ts et Importa- teurs d'Huiles Essentielles oi Grasse the methods of the Scientific Section of the Essential Oil Association of the United States of America the various pharmacopceias such as the B.P. 1953, the B.P. Codex 1954, and the U.S.P. XIV. Having determined the various.physical and chemical characters, the literature will have to be consulted to see if the values found for the sample of essential oil falls within the usually accepted limits as given by Gildemeister and Hoffmann, "Die •ltherische Ole," 3rd edition Guenther, "The Essential Oils," Volumes 1-6 Parry, "The Essential Oils" "The Handbook of Standards" issued from Grasse, and the Standards issued by the Essential Oil Association of U.S.A. (both mentioned previously) while a very concise and authoritative summary of all aspects of essential oils is given in the section on Huiles Essentielles, by Y. R. •aves, in "Traite de Chimie Organ- ique," Tome XVI, by Grignard, Dupont et Locquin. Tests for possible additions and adulterations can also be carried out. While the results of the analysis may lead to some samples being rejected, there will be several samples that will pass this first stage of the examination, and here again it must be stressed that the deciding test will be an olfactory or taste test. This test is adapted to the use to which the oil is intended. With oil intended for the beverage trade, the sample should be made into a soluble essence by shaking one volume with four volumes of 70 per cent ethyl alcohol and using the resulting lower layer at the rate of 1 to 2 ounces to a gallon of mineral water_syrup (6 lb. of sugar in a gallon of syrup acidified with 2 ounces of citric acid per g•llon) and diluting the resulting syrup with water at the rate of 1« ounces of syrup up to half-pint with plain or aerated water. If the oil is intended for the confectionery trade it can be tested in Iondant at a rate of 1 in 10,000, or if the oil is intended for high boilings a small batch of boiled sweets should be made in the laboratory to see that the oil reacts favourably to heat treatment. Similarly for the flour confectionery trade a small cake or some biscuits should be made, baking to the same temperature at which the oil is eventually intended to be used. 261