ISO INTERNATIONAL STANDARD 279 Second edition 1998-12-15 Essential oils Determination of relative density at 20 °C Reference method Huiles essentielles Détermination de la densite relative a 20 °C - Methodedereférence ISO Reference number ISO 279:1998(E) ISO 279:1988(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (isO member bodies). The work of preparing International Standards is normally carried out through iSO technical liaison with iSO, also take part in the work. SO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. InternationalStandardsaredraftedinaccordancewiththerulesgivenintheISO/lECDirectives,Part3 Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 279 was prepared by Technical Committee ISO/TC 54, Essential oils. This second edition cancels and replaces the first edition (IsO 279:1981), which has been technically revised. @ISO1998 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. InternationalOrganizationforStandardization Case postale 56· CH-1211 Geneve 20 · Switzerland Internet [email protected] Printed in Switzerland ii ISO 279:1998(E) INTERNATIONAL STANDARD @ISO Essential oils Determination of relative density at 20 'C - Reference method 1 Scope This International Standard specifies the reference method for the determination of the relative density of essential oils at 20 °C. NOTE If it is necessary to perform the test at a different temperature on account of the nature of the essential oil, the temperature should be mentioned in the International Standard appropriate to the essential oil concerned. The average 2 Normative reference this International Standard. For dated references, subseqent amendments to, or revisions of, this publication do not possibility of applying the most recent edition of the normative document indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IEC and IsO editions maintain registers of currently valid International Standards. IsO 356, Essential oilsPreparation of test samples 3 Terms and definitions For the purposes of this International Standard, the following terms and definitions apply 3.1 relative density at 20 °C ratio of the mass of a given volume of the oil at 20 C to the mass of an equal volume of distilled water at 20 °C NOTE This quantity is dimensionless and its symbol is d20. 3.2 absolute density at 20 °C of an essential oil ratio of the mass of a given volume of the oil at 20 °C to the same volume NOTE This quantity is expressed in grams per millilitre. 4 Principle Equal volumes of the essential oil and water, at 2o °C, are weighed successively in a pyknometer.