_Starch._--A convenient method for estimating the starch is to first remove the fatty matter of the cocoa by exhaustion with petroleum-naphtha, and then boil the residue with alcohol. The remaining insoluble matter is dried, and afterwards boiled until the starch becomes soluble. It is next again boiled for several hours with a little dilute sulphuric acid, after which the solution is purified by addition of basic plumbic acetate. The liquid is then treated with sulphuretted hydrogen, in order to remove the lead, and the sugar contained in the filtered solution is determined by means of Fehling’s solution, and calculated to terms of starch. The proportion of starch normally present in cocoa is to be deducted from the results thus afforded. The variety of starch contained in cocoa differs in its microscopic appearance from the starches most frequently added. _Sugar._--The sugar may be determined by evaporating the alcoholic solution obtained in the preceding process, and then subjecting the residue to the same method of procedure. The proportion of woody fibre in cocoa can be approximately estimated by the method of Henneberg and Stohman,[17] which consists in extracting the fat with benzole, boiling the remaining substances for half an hour, first with 1·25 per cent. sulphuric acid, then with 1·25 per cent. solution of potassium hydroxide. The residue is washed with alcohol and with ether, and its weight determined. Unwashed cocoa-berries, when treated in this manner, gave from 2 to 3 per cent. of cellulose, while cocoa husks furnished from 10 to 16 per cent. The presence of chicory in soluble cocoa and chocolate is easily recognised by the dark colour of the extract obtained, upon digesting the suspected sample with cold water; ochres and other colouring matters are detected by the reddish colour of the ash as well as by its abnormal composition. The addition of foreign fats to chocolates is stated to be occasionally resorted to. The melting point of pure cocoa-butter varies from 30° to 33°. The identification of foreign fats can sometimes be accomplished by means of their higher melting point, and by an examination of the separated fat, according to Koettstorfer’s method (see p. 71). The table following gives the melting points of various fats, and the number of milligrammes of K(OH) required for the saponification of one gramme of the same.