Entering now, and turning into the private station, we see thousands of sacks of the freshly-imported beans being transferred to the neighbouring stores. The new arrivals
must first be sifted and picked over to get rid of any that may be unsound, or of any foreign material still remaining. This is accomplished by a sorting and winnowing machine, which delivers by separate shoots the cleaned beans, graded according to size, and the dust and foreign matter.
A battery of roasters await the survivors of this operation, which are automatically conveyed to the hoppers. High-pressure steam supplies the requisite heat without waste or smoke, and as the huge drums slowly rotate, experienced workmen, on whose judgment great reliance is placed, carefully watch their contents, and decide when precisely the right degree of roasting has been attained to secure the richest aroma. Then they are passed through a cooling chamber, after which they are in condition for "breaking down."
This consists in cracking the shells of the beans, and releasing the kernels or "nibs," from which the shells and dust are winnowed by a powerful blast. It is accomplished by carrying the beans mechanically to the cracking machine
at a considerable height, whence husks and nibs are allowed to fall before the winnower: the separated nibs are assorted according to size. Some of the shells find their way to the Emerald Isle, to be used by the peasants for the weak infusion called "miserables."
Now comes the important process of grinding, performed between horizontal mill-stones, the friction of which produces heat and melts the "butter," while it grinds the "nibs" till the whole mass flows, solidifying into a brittle cake when cold.
The thick fluid of the consistency of treacle flowing from the grinding-mills is poured into round metal pots, the top and bottom of which are lined with pads of felt, and these are, when filled, put under a powerful hydraulic press, which extracts a large percentage of the natural oil or butter. The pressure is at first light, but as soon as the oil begins to flow the remaining mass in the press-pot is stiffened into the nature of indiarubber, and upon this it is safe to place any pressure that is desired. As it is not advisable to extract all the
butter possible, the pressure is regulated to give the required result. In the end a firm, dry cake is taken from the press, and when cool is ground again to the consistency of flour; this is the "cocoa essence" for which the firm of Cadbury is so well known in all parts of the world.[13]
Between cocoa and chocolate there are essential differences. Both are made from the cocoa nib, but whereas in cocoa the nibs are ground separately, and the butter extracted, in chocolate sugar and flavourings are added to the nib, and all are ground together into a paste, the sugar absorbing all the superfluous butter. If good quality cocoa is used, the butter contained in the nib is all that is needful to incorporate sugar and nib into one soft chocolate paste for grinding and moulding, but in the commoner chocolates extra cocoa butter has to be added. It is a regrettable fact that some unprincipled makers are tempted to use cheaper vegetable fats as substitutes for the natural butter, but none of these are really
palatable or satisfactory in use, and none of the leading British firms are guilty of using such adulterants, or of the still more objectionable practice of grinding cocoa-shells and mixing them with their common chocolates.[14]