Estimations of the amount of sugar obtained upon boiling the suspected coffee with water containing a little sulphuric acid (see p. 37), and the proportion of the sample which is soluble in hot water should be made. The presence of chicory is shown by a decided increase in the amount of soluble substances; that of rye, by the notable quantity of sugar produced by the inversion with acid, due to the starch contained in the grain. In this connection, the following determinations of Krausch are of interest:-- ---------------------------------+----------+------------+---------- |Substances|Ready-formed| Sugar |Soluble in| Sugar. | after | Water. | |Inversion. ---------------------------------+----------+------------+---------- | per cent.| per cent. | per cent. Roasted coffee | 23·81 | 0·20 | 24·59 „ chicory | 65·42 | 23·40 | 22·14 „ rye | 31·92 | .. | 75·37 „ coffee | | | + 10 per cent. chicory | 30·63 | 2·30 | 23·15 „ coffee | | | + 10 per cent. rye | 25·98 | 0·19 | 29·60 ---------------------------------+----------+------------+---------- The presence of roasted rye, corn, and other grains in coffee, may be qualitatively recognised by testing the cold infusion of the sample with iodine solution for starch, which is not contained in a ready formed state in coffee. Caffeine is absent in chicory and the other usual adulterants of coffee, and the estimation of this alkaloid is of decided service (see p. 21). Roasted coffee contains about 1 per cent. of caffeine. A popular brand of ground coffee received by the author for examination, and labelled “Prepared Java Coffee,” had the following approximate composition:--Coffee, 38; peas, 52; rye, 2; and chicory, 7 per cent. A sample of “acorn” coffee, analysed by König, gave the following results:-- Per cent. Water 12·85 Nitrogenous substances 6·13 Fat 4·01 Sugar 8·01 Other non-nitrogenous substances 62·00 Cellulose 4·98 Ash 2·02 The non-nitrogenous constituents contained from 20 to 30 per cent. of starch, and from 6 to 8 per cent. of tannic acid. The composition of the well-known German coffee-substitutes, prepared by Behr Bros., is stated to be as follows:-- “_Rye Coffee-substitutes._”