The phosphoric acid method for the determination of cineol in Eucalyptus oils was originally discovered by Mr. L. R. Scammell, of Adelaide, South Australia, in 1892, and was the outcome of an investigation on various samples of cheap oils then being placed on the market. The process was used by Messrs. Faulding & Co. for the manufacture of Eucalyptol, or cineol, which they shipped to England. In 1894 the process was patented by Mr. Scammell, as Faulding's

Process, in England, France, Germany, and America, as well as in the Australian colonies. With this method available it was possible to introduce a standardised oil containing a guaranteed quantity of cineol, and to this end Messrs. Faulding & Co. instructed their agent in England to call upon every retail chemist in London, in order to explain the phosphoric acid method for testing Eucalyptus oils.

This method is convenient, and with ordinary care can be carried out with fair success, particularly with Eucalyptus oils required to pass the official standards, in which much cineol is now demanded. Although the method does not indicate absolutely the actual amount of cineol present, yet, when undertaking the work for the first edition, we found it most useful for arranging the oils of the several members of the genus into groups, for the purpose of classification. Unfortunately the method is not very satisfactory, for quantitative purposes, when only a small amount of cineol is present, and it is necessary in such cases to fractionate the oils and determine the amount of cineol in the most suitable fraction. With the oils of many species the method cannot be employed, as the cineol is too small in amount.

The phosphoric acid method is official in the British Pharmacopoeia and is there directed to be carried out in the following manner: - " When 10 millilitres of the oil are mixed with 4 to 5 millilitres of syrupy phosphoric acid in a vessel surrounded by a freezing mixture, and then pressed strongly in a piece of fine calico between folds of blotting paper, the pressed cake decomposed by warm water in a graduated vessel yields an oily layer which on cooling to 15.5° C. measures not less than 5.5 millilitres (presence of not less than 55 per cent. of cineol)."