True ground cinnamon (see Figs. 22 and 23, Chap. III) consists of long cells of woody fiber which represent the thin layers found in the bark and scattered through it, consisting of a little starch in stellate cells. There is nothing more distinct between cinnamon and cassia than the amount of volatile oil the bark contains, and yet some of the inferior cinnamon bark does not contain as much volatile oil as does good cassia, but cinnamon oil is of a much higher and more delicate aroma. It is hard to detect cassia (see Fig. 41, Chap. III; adulterated, Fig. 46) in ground cinnamon, as the flavor is so similar, but the cassia contains but little wood fiber and few stellate cells and the presence of starch is more marked. To test cinnamon, experts are required. The usual test is by chewing, but this method soon makes the mouth sore. The most inferior ground cassia, however, bears such a close resemblance to the best cassia and to the true cinnamon that it may be substituted for it or used as an adulterant without being easily detected. The following instructions are useful in examining powdered cinnamon. Make a decoction of pure ground cinnamon, also a decoction of the suspected mixture, and filter both; when cold add to thirty grams of each one or two drops of iodine, when the decoction of pure cinnamon will be but slightly affected while the mixture will assume a blackish-blue coloration. Although much depends upon the age of the oils, the greater the age of the oil the smaller the quantity of iodine solution absorbed by it. The cheap sort of cassia, or “Cassia Vera,” can be distinguished from China cassia and from true cinnamon by its richness in mucilage, which can be extracted by cold water as a thick glary liquid, which on the addition of corrosive sublimate or neutral acetate of lead yields a dense viscous precipitate. The most reliable test for cassia in true cinnamon is to obtain the proportion of ash in each, the ash in cinnamon being 4.59 and 4.78 per cent., cassia lignea giving but 1.84 and “Cassia Vera” nearly the same as cinnamon, 4.08. Another test is to ascertain the amount of ash soluble in water. The quantities are 25.04, 28.98 per cent. in whole cinnamon, about 18 per cent. in chips, and 8.15 in “Cassia Vera,” and 26.40 in cassia lignea. Again the proportion of oxide of manganese is never more than 1 per cent. (0.13-0.97) in cinnamon, but it is over (1.13-1.53) in “Cassia Vera” and 3.65-5.11 in cassia lignea. The cinnamon ash will always be found white or nearly so, while both the cassia ashes are gray or brown and yield an abundance of chlorine on heating with hydrochloric acid. The cinnamon or cassia in the bark is easily distinguished, as the inferior kinds are thicker and appearance coarser and their color darker brown and duller and have a more pungent taste, which is less sweet than the true cinnamon, succeeded by a bitter taste.