Cider is obtained by the fermentation of the juice of fresh apples. According to the definition adopted by the International Congress for the repression of food adulteration (Geneva, 1908 and 1909) a proportion of pears, not exceeding 10 per cent., may be mixed with the apples, and the juice may be extracted either with or without the addition of water. If without, the product is distinguished as "pure juice" cider. "Sparkling" cider, according to the Congress, should have been fermented in bottle, as distinguished from "aerated" cider, into which carbonic acid has been directly intro. duced. "Small" cider is defined as cider containing from 2 to 4 per cent. of " total "alcohol - that is, alcohol both actually existing, and potential in the sugar present; with an extract value, when the sugar is deducted, ranging from 0'8 to 14 grams per 100 c.c., and ash 008 to 014 gram per 100 c.c.

In France, the regulations require that "cider "must contain at least 3'5 per cent. of alcohol, actual or potential, 12 grams of extract (sugar deducted), and 012 gram of mineral matters (ash) per 100 c.c. If any one of these constituents falls below the limits given, the product must be termed "small " cider (" petit cidre "). There are no special regulations for cider in this country.

In making cider, the apples are crushed in a mill, and the resulting pulp, wrapped in cloth, is pressed to force out the juice. Two or three pressings may be given, and the pulp may be moistened with water between two pressings. The richness of the juice in sugar, and therefore in the potential amount of alcohol, depends upon the variety of apple used; mediocre fruit yields juice of sp. gr. about 1.045 to 1.055 and containing 9 to 12 per cent. of sugar; while the best kinds give juice of sp. gr. 1080 to 1090 or above, with 16 to 18 per cent. of sugar, or more. Addition of sugar, tannin, tartaric acid, ammonium phosphate (20 grams per hectolitre), and treatment with sulphurous acid and alkali bisulphites, are regarded by the International Congress as regular operations in the process of manufacture, as are also the sweetening of the resulting cider with crystallised sugar, its pasteurisation, clarification, colouring with caramel, and treatment with citric acid. The French regulations limit the amount of added tartaric acid or citric acid to 005 gram per 100 c.c., and of alkali bisulphites to 001 gram, with the further condition that the cider shall not retain more than 0.01 gram of total sulphurous anhydride, free or combined, per 100 c.c. Colouring with cochineal, caramel, and chicory-infusion is recognised.

The sugars in the juice of ripe apples comprise saccharose, dextrose, and lævulose. These exist in varying proportions, the lævulose, however, being the largest constituent. The saccharose represents about 5 to 39 per cent. of the total sugars; and in the remainder, the proportion of lævulose to dextrose ranges from 10 to 1 down to about 3 to 1. In the progress of fermentation, the cane-sugar becomes inverted, and the original dextrose may be fermented out completely, leaving only lævulose and more or less invert-sugar, or perhaps lævulose only.

The important constituents of cider "must" other than the sugars and the small quantities of esters or essential oils to which the characteristic apple flavour is due, are the acids, pectins, and tannins. According to a table drawn up by the French " Association Pomologique," the must from eleven different varieties of apples recommended for the making of cider yielded the following data: -

Some English cider-musts analysed by A. H. Allen1 gave the following results: -

1 Analyst, 1902, 27, 183.

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These samples were analysed about thirty-six hours after the juice had been pressed, and contained a little alcohol, ranging up to 1.13 per cent. The "glucose" presumably represents the whole of the reducing sugars present, including any inverted saccharose.

In a report1 upon the results of investigations into cider-making, carried out on behalf of the Bath and West and Southern Counties Society, F. J. Lloyd gives the composition of the juice from a large number of varieties of apples grown in this country. It is not stated, however, which kinds are chiefly used in cider-making. The juice from the variety known as "Kingston Black " gave the following results: -

The results represent apples of the variety in question grown in ten different years.

For the analysis of cider, the methods described for wine are applicable, so far as they may be required. The following processes are also useful.