In the other method, the oil is first extracted from the seeds by hydraulic pressure, which leaves a sort of cake. This cake is then broken up and pounded in a mortar. It is then sifted, that going thru the sieve being a kind of bolted mustard flour. The remaining bran is then mixed with an equal quantity of wheat flour, one per cent of cayenne and sufficient turmeric to give the proper color. This is pounded and treated as before, the process being continued until there is no bran left. Then all the different siftings are mixed together, giving a mixture of about equal proportions of mustard and wheat flour, with the cayenne and turmeric added in proper quantities. The peculiar pungency and odor, to which mustard owes much of its value, are due to an essential oil developed by the action of water on two chemical substances contained in black mustard seed; one called sinigrin and the other myrosin. The latter substance in the presence of water acts as a sort of ferment on the sinigrin, and it is worthy of remark that this reaction does not take place in the presence of boiling water and, therefore, it is not proper to use very hot water in the preparation of mustard, cold water only should be used. White mustard seed contains in the place of sinigrin a peculiar acrid substance called sinalbin and also a trace of myrosin, therefore, it possesses very little pungency and it produces a larger percentage of flour than the black. The proper blending of these two seeds is necessary to the production of the best mustard, as the white has the peculiar ferment within it which develops to the highest degree the flavor of the black. The reason for mixing wheat flour, rice flour or other farina with pure mustard flour is, that owing to the large amount of oil contained in the latter it will not keep long, but turns rancid, ferments and cakes; the added farinas by absorbing a portion of the oil retards fermentation, decomposition and rancidity. They should not be looked upon as adulterants, unless added in too great quantities, and the price of the mustard should be in proportion to the added absorbents. A mean form of adulteration is to mix gypsum and chrome yellow with the ground mustard seed. If upon the addition of a small quantity of iodine to ground mustard it turns blue, it shows that starch is present. The ammonia test will show the presence of turmeric. Every manufacturer has his own particular formula, and consequently there are many different qualities, both in the pure mustard and the compounds. One is composed of 37 per cent brown and 50 per cent white mustard flour, 10 per cent of rice flour, 3 per cent of black pepper, a little Chili pepper and ginger. Pure mustard oil, as pressed from the seed, is not pungent and will not blister unless mixed with water.