The art of jam and jelly making was formerly domestic, but has become a very large branch of manufacture. For the production of a thoroughly satisfactory conserve the boiling-down must be carried out very rapidly, so that the natural colour of the fruit shall be little affected. Considerable experience is required to stop at the right point; too short boiling leaves an excess of water, leading to fermentation, while over-concentration promotes crystallization of the sugar. The manufactured product is on that account, as a rule, more uniform and bright than the domestic article. The finish of the boiling is mostly judged by rule of thumb, but in some scientifically conducted factories careful thermometric observation is employed. Formerly jams and jellies consisted of nothing but fruit and sugar; now starch-glucose is frequently used by manufacturers as an ingredient. This permits of the production of a slightly more aqueous and gelatinous product, alleged also to be devoid of crystallizing power, as compared with the homemade article. The addition of starch-glucose is not held to be an adulteration. Aniline colours are very frequently used by manufacturers to enhance the colour, and the effect of an excess of water is sought to be counteracted by the addition of some salicylic acid or other preservative. There has long been, and still exists to some extent, a popular prejudice in favour of sugar obtained from the sugar-cane as compared with that of the sugar-beet. This prejudice is absolutely baseless, and enormous quantities of beet-sugar are used in the boiling of jam. Adulteration in the gross sense, such as a substantial addition of coarse pulp, like that of turnips or mangolds, very rarely occurs; but the pulp of apple and other cheap fruit is often admixed without notice to the purchaser. The use of colouring matters and preservatives is discussed at length in the article ADULTERATION. (O. H.*)