_Maumené’s test._--This test is founded upon the fact that the elevation of temperature caused by mixing olive oil with strong sulphuric acid is considerably less than that produced with the oils commonly employed as its adulterants. With these latter an evolution of sulphurous acid generally takes place, which is not the case with pure olive oil. The best method of procedure is as follows:--10 c.c. of sulphuric acid (sp. gr. 1·844) are gradually added to 50 grammes of the sample, the mixture being constantly stirred with a small thermometer, and observations made of the maximum increase of temperature produced, as well as of the evolution of gas. When treated in this manner, genuine olive oil causes an elevation of about 42°; that given by various other oils, often added to it, ranges from 52° to 103°, and it is frequently possible to recognise their presence in admixtures by the high temperature produced. The following are the increases of temperature observed by L. Archbutt:--olive, 41-45; rape, 55-64; arachis, 47-60; sesamé, 65; cotton-seed (crude) 70; (refined), 75-76; poppy-seed, 86-88; menhaden, 123-128. In the Paris Municipal Laboratory an acid of 1·834 sp. gr. is used, and the following heating powers are regarded as standards:--For olive oil, 55·5°; for cotton-seed, 69·5° for nut, 62°; for sesamé, 66°; for poppy oil, 73°. The application of Hubl’s test for butter (see p. 75) is one of the most useful means for the detection of foreign oils in olive oil. The iodine absorption number of the pure oil is considerably below that of its most common adulterants. The prevalence of the adulteration of olive oil has been abundantly demonstrated. Of 232 samples examined by the New York and Massachusetts State Boards of Health, 165 (71 per cent.) were spurious. It is a notorious fact that large quantities of cotton-seed oil are exported from the United States to France and Italy, much of which returns home under the guise of the genuine product of the olive. FOOTNOTES: [136] It has been stated that American olive oil of superior excellence is made in the States of N.C., Miss, and Cal.; but this product does not, as yet, appear to be generally known on the New York market. [137] Frens. Zeitsch. 3, 1864, p. 513. MUSTARD. Mustard is the product obtained by crushing and sifting the seeds of _Sinapis nigra_ and _Sinapis alba_, of the genus Brassicaceæ. In the manufacture of the condiment, both the black and white seeds are used. According to analyses made by Piesse and Stansell,[138] fine grades of the two varieties of mustard possess the following composition:--