The procedure in Eminger’s process is as follows: 10 grammes of powdered bean of cacao preparation are placed in a weighed glass flask, then stirred up with 100 grammes of petroleum ether and allowed to settle. The petroleum ether is next carefully poured off, without disturbing the sediment, and the treatment repeated several times. After the last decantation, the residue is well drained, then dried in the flask and weighed. The difference in weight of the residue and the former figure represents the amount of fat. An aliquot portion of the residue (about 5 grammes) is then boiled with 100 grammes of a 3-4 percent strong sulphuric acid in a flask connected with a reflux condenser, until cacao red is given as a resultant, a task which occupies three quarters of an hour. The contents of the flask are then poured into a beaker, and neutralised, whilst hot, with barium hydroxide. The whole is then mixed with sand in a basin and evaporated to dryness; afterwards the dry residue is introduced into a Soxhlet apparatus on a paper cone, and there extracted for 5 hours with 150 grammes of chloroform. The latter is carefully distilled off and the residue dried for a period of one hour at 100° C. As previously stated, the separation of the two diureides is not necessary and in commercial analyses it is sufficient to state the amount of each separate substance after the removal of fat by means of some suitable solvent. But should the splitting up be desired, then Eminger’s method should be adopted, which depends on the solubility of caffeine in carbon tetrachloride.[180] With that object, the mixture of fat, theobromine and caffeine is treated in the flask with 100 grammes of carbon tetrachloride and repeatedly agitated for one hour. After filtration, the carbon tetrachloride, which now contains fat and caffeine, is distilled off. The theobromine left undissolved in the flask and the filter used to filter the carbon tetrachloride solution are then extracted with boiling water, the solution is filtered and evaporated to dryness, the residue representing theobromine. The separation of caffeine and theobromine can also be effected by cautious treatment with caustic soda, so dissolving the theobromine and leaving the caffeine untouched in its entirety.[181] (Cf. Riederer.) 7. ~Determination of Starch.~ This can only be of importance in rarer instances, as the starch naturally present in raw cacao generally varies between 9 and 10 percent, and there is no chemical method of separating foreign matter from cacao starch. But should the necessity arise, a determination can be carried out as follows.