A cyclopaedia of practical receipts, and collateral information in the arts, manufactures, professions, and trades, including medicine, pharmacy, and domestic economy : designed as a comprehensive supplement to the pharmacopœias, and general book of reference for the manufacturer, tradesman, amateur, and heads of families / by Arnold J. Cooley.
- Arnold James Cooley
- Date:
- 1856
Licence: Public Domain Mark
Credit: A cyclopaedia of practical receipts, and collateral information in the arts, manufactures, professions, and trades, including medicine, pharmacy, and domestic economy : designed as a comprehensive supplement to the pharmacopœias, and general book of reference for the manufacturer, tradesman, amateur, and heads of families / by Arnold J. Cooley. Source: Wellcome Collection.
Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.
1295/1368 (page 1277)
![should be chosen for this purpose; prefer- ence being given to the bitartrate of potassa, on account of its presence in the grape. The addition of any of these substances to a saccharine solution renders its fermenta- tion l)oth more active and complete. The favorable influence of cream of tartar on fermentation was first pointed out by Thenard and Colin, and the addition of a little of this article has been adopted in practice, veith manifest advantage, by the manufacturers of British wine. When the acidity caused by these acids, or their acidu- lous salts, in a ferment, is considerable, the animal and mineral poisons, the essential oils, and various other substances, cease to modify the fermentation ; while, at the same time, the resulting alcohol is obtained in a purer state, as the extraneous products which we have just mentioned, are either not formed at all, or only in small and un- important quantities. The contrary takes place when the ferment is rendered neutral by washing it with water, or, when, owing to partial spontaneous decomposition, it exercises an alkaline reaction on test paper. It then ceases to excite the alcoholic fer- mentation in solutions of cane-sugar, and instead thereof, induces the development of lactine (sugar of milk), lactic acid, 8fc.; in this respect exercising a similar action on solutions of sugar to that of caseine, diastase, and animal membrane. There is good reason for supposing that each variety of sugar which is susceptible of the alcoholic fermentation, is first con- verted into grape sugar, by contact with the ferment, and that this variety of sugar, is alone capable of yielding carbonic acid and alcohol. (Liebig.) During this conversion of grape sugar, it is presumed that one of its atoms, (represented, in the crystallized state, by C,2 H,, 0,4), loses two atoms of water, and vields (according to theory) 44-84g of c'arlwyiic acid, 47-12g (49-38, Thenard,) of alcohol, and 9'04g of water, which nearly agrees with the experiments of Guerin-Varry. According to Gay-Lussac, 45 lb. of sugar are converted into 23 lb. of alcohol, and 22 lb. of carbonic acid. This explanation will be simplified by reference to the following diagram :— 4 atoms of carbonic acid =64 . Og 2 „ alcohol =Cg H,2 O4 1 „ grape sugar, 1 p „ r, dried at 212° = ] ^'^ ^'^ From the above it will be readily seen, that by a new grouping of the elements of grape-sugar, alcohol and carbonic acid are produced, without the elements of the body which excites the fermentation taking any part in the conversion. The circumstances most favorable to this fermentation, are — a certain degree of warmth—a sufficient quantify of active fer- ment, and its due distribution through the liquor. The temperature of from 68° to 77°Fahr. is usually regarded as the most pro- pitious for the commencement and progress of fermentation ; but it has been ably shown by Liebig, that, at this temperature, the newly formed alcohol slowly undergoes the acetous fermentation, forming vinegar, by which the vinous character of the liquor is lessened. This conversion of alcohol into vinegar proceeds most rapidly at a tempera- ture of 95° Fahr., and gradually becomes more languid, until, at about 46° to 50° Fahr. (8 to 10 Cent.), it ceases altogether, while the tendency of the nitrogenous sub- stances to absorb oxygen at this low tem- perature is scarcely diminished in a percep- tible degree. It is therefore evident, that if wort (or any other saccharine solution), is fermented in wide, open, shallow vessels, as is done in Bavaria, which afford free and unlimited access to the atmospheric oxygen, and this in a situation where the tempera- ture does not exceed 46° to 50° Fahr., a separation of the nitrogenous constituents, i. e., the exciters of acidification, takes place simultaneously on the surface, and within the whole body of the liquid. (Liebig.) By this method wine or beer is obtained, which is invariably far superior in quality to that fermented in the usual manner. The symptoms of a perfect fermentation of malt wort, according to the usual English system with top yeast (oberhefe), have been thus described by a well-known practical writer on brewing.—1. A cream-tike sub- stance forms round the edges of the gyle tun, which gradually extends itself, and ulti- mately covers the whole surface of the liquor.—2. A fine curly, or cauliflower-head, in a similar way extends itself over the sur- face, and indicates to the experienced brewer the probable quality of the fermentation.— 3. The stomach, or vinous odour, is next evolved, and continues to increase with the attenuation of the wort. Tlie peculiar nature of this odour is also an indication of the state of the fermentation.—4. The cauliflower-head changes, or rises to a fine rocky or yeasty head, and ultimately falls down.—5. In this stage the head as- sumes a peculiar yeasty appearance, called by brewers close-yeasty, and the gas is evolved in sufficient quantity to blow up little belts or bladders, which imnie-](https://iiif.wellcomecollection.org/image/b21535528_1295.jp2/full/800%2C/0/default.jpg)
