Encyclopaedia Americana: a popular dictionary of arts, sciences, literature, history, politics and biography, brought down to the present time : including a copious collection of original articles in American biography : on the basis of the seventh edition of the German Conversations-Lexicon (Volume 5).

Date:: 1830-33

Credit: Encyclopaedia Americana: a popular dictionary of arts, sciences, literature, history, politics and biography, brought down to the present time : including a copious collection of original articles in American biography : on the basis of the seventh edition of the German Conversations-Lexicon (Volume 5). Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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rIcoHoI and carlionic acid. When any liquid has undergone the vinous fermen- tation, or even pure alcohol, diluted with water, is mixed with yeast, and exposed in a warm jjlace to the open air, the acetous fermentation takes place. This change is attended with an intestine movement, and the developement of heat and carbonic acid gas ; the fluid, at the same time, be- coming turbid, from the deposition of a peculiar filau)entous matter. This pro- cess goes on tardily below 60° Fahr.; at 50°, is very sluggish ; and at 32°, is wholly arrested. Ou the contrary, when the tem- jjtrature is as high as 80°, it proceeds with vigor. It is necessary to distinguish be- tween the mere formation of acetic acid, and the acetous fermentation. Most veg- etal)le substances yield acetic acid, when they undergo spontaneous decomposition ; and inferior kinds of ale and beer are known to acquire acidity in a short time, even when confined in well corked bot- tles. These processes, and a variety of others, liowcver, are quite different from the proper acetous fermentation, above described, being unattended with visible movement in the liquid with the absorption of oxygen from tJie air, or the evolution of carbonic acid. The true acetous fer- mentation consists in the conversion of alcohol into acetic acid, the quantity of the latter being precisely proportional to that of the former. The nature of the chemical action is, however, at present, obscure. It has been imagined that ])ure alcohol contains a greater proportional quantity of carbon and hydrogen than acetic acid; that the oxygen of die atmos- phere, the presence of which is indispen- sable, al>stracts so much of those elements, by giving rise to the formation of carbonic acid and water, as to leave the remaining carbon, hydrogen and oxygen of the alco- hol, in the precise ratio for forming acetic acid. The acetous fermentation is con- ducted on a large scale, for yielding the common vinegar of commerce. In France, it is prepared by exposing weak wines to the air during warm weather. In Eng- land, it is made from a solution of brown sugar or molasses, or an infusion of malt. The vinegar thus obtained, however, al- ways contains a large quantity of muci- laginous and other vegetable rnattere, the presence of which renders it liable to sev- eral ulterior changes. In this country, it is more generally the product of cider. The putrefactive fermentation is confined to those vegetable substances, ui which the oxygen and hydrogen exist, in a pro- portion to form water; and in such, par- ticularly, as contain nitrogen. Those proximate principles, in which carbon and hydrogen prevail, such as the oils, resins, and alcohol, do not undergo the putrefac- tive fermentation; nor do acids, which contain a considerable excess of oxj'gen, manifest a tendency to suffer this change. The conditions requisite for enabluig the putrefactive process to commence, are moisture, air, and a certain teniperature. The temperature most favorable is be- tween 60° and 100° Fahr. The products of the process may be divided into the solid, liquid and gaseous. The liquid are chiefly water, together with a little acetic acid and oil. The gaseous products are light, carbureted hydrogen, carbonic acid, and, when nitrogen is present, ammonia. Pure hydrogen, and, probably, nitrogen, are sometimes disengaged. Another clas- tic princij)le, supposed to arise from pu- trefying A egetable remains, is the noxious miasmata of marshes. The origin of these, liowever, is exceeding!}' obscure. The solid product is a dark, pulverulent substance, consisting of charcoal, com- bined with a little oxygen and liydrogen, which, when mixed with a proj)cr quan- tity of earth, is called vegetable mould. Fernandez, or Juan Fernandez, an island in the South Pacific ocean, about llOleagues west of Chile; about 4 leagues long, and hardly 2 wide ; of an irregular shai)e ; Ion. 78° 52' W.; lat. 33° 40^ S. It is noted for the refreshments it has af- forded to navigators from its wild goats, vegetables and water. The governor of the island is appointed by the president of Chile.—Alexander Selkirk, a Scotch sailor, being left on this island by his cap- tain, lived here from the year 1705 to 1709 in solitude. This circumstance gave rise to the celebrated romance of Robuison Cru- soe, by De Foe. Fernando de Noronha, or Naronho ; an island in the Atlantic, full of moun- tains, which have the apj)earance of vol- canoes, but are covered with verdure; not above three miles in length, and in shape resembling a laurel leaf; about 210 miles from the coast of Brazil ; Ion. 32° 38' W.; lat. 3° 56' S. It is defended with forts. The water is in general brackisli, and sometimes no rain falls for three or four yeare together. It is a place of ban- ishment for male criminals: no females are jjermitted to visit the island. The garrison, consisting of about 120 men, is relieved yearly. Fernando Po, or Fernand Pao ; an island of Africa, in the Atlantic, near the coast of Benin, about 60 miles in circum-

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