CORK cutting, or the manufacturing of corks. This business, though it is thought one of the most dirty, is not one of the least profitable ; it is likewise easy in the acquirement. The cork, after being press ed into square pieces, is received by the cork cutters, and if not sufficiently flat for their purpose, they "lay" it again over a fire in their "burning-yard," turn ingthe convex part to the flame ; the heat, by twisting the edges of the bark, coun teracts the natural bend, and compels it to receive a flat form. During this ope ration, a considerable degree of attention is paid to smoothing it, and particularly again to cover its defects. It is next cut into slips, narrow or wide, according to the intended cork, bung, or tap, for such •are the names of the general divisions in this business. The use of the two former is well known, the latter is used for stop ping the tap-holes of barrels, as the name implies. These slips are again cut into squares, of a length proportioned to the use they are intended for. This opera tion is performed by one man, from whom they are handed forward to several others. A further division of corks takes place of three different sorts, according to their lengths, and are denominated "short," " short long," and "full long." The cork maker places himself before the table or plank, on which is fastened a board about three inches thick, four broad, and twelve long : immediately on a line with his left hand is a piece of wood rising about four inches from the board, and fixed about the middle of it, on which the cork is laid after being cut as above. This wood not only supports the cork, and is as a guide to the workman, but by its elevation above the board gives room for the knife to cut a part of the cork in a smooth and circular man ner, without striking on the table below. The piece is then turned to where the last cut ceased, and this is continued until the knife has gone completely round ; the top and bottom are then pared level, and the cork thrown into a box or basket with the rest of the same length. As the bark is not of th e same quality throughout each piece, the corks are sorted by a boy into four kinds, "superfine," "fine," "common," and "coarse," and are sold accordingly. The only tool employed by the cork-cut .ter is a knife about three inches broad in dehe blade, and about six inches long, very Rhin and sharp, and equal in breadth from the handle nearly to the end, which is finished by a gentle curve. This knife he sharpens upon the board where the guard is placed, by one whet or stroke op each side, after every cut, and now and then upon a common whetstone.
From the foregoing review, it is evi dent that the art of a cork-cutter is prin cipally to obtain a regular, round, and quick turn of the wrist, in guiding the knife so as to complete a pretty correct circle, and to make a smooth surface ; it is on this account that the knife must be particularly sharp, to enable the workman to turn it with ease. Cork received into
the stomach, in its crude state, is very de leterious : but after it has undergone cer tain processes, it is used in medicine. It contains a small quantity of very power ful acid, called suberic acid. This acid may be obtained in a solid form, but is not crystallizable : it is either pulverulent when it has been precipitated, or when obtained by evaporation is in thin irregu lar pellicles. Its taste is slightly bitter and acid : dissolved in a small quantity of boiling water, it is irritating to the throat, and excites coughing. It reddens the vegetable colours, and it attracts a little humidity from the air, especially when it is not perfectly pure. Exposed to heat, it is volatilized, and forms crystalline flakes on the sides of the vessel. Heated by the blow-pipe, it first liquifies, then becomes pulverulent, and lastly is sublimed, exha ling an odour of sebacic acid. It becomes brown from exposure to light. At the tem perature of 60°, an ounce of water dis solves ten grains of the concrete acid, but if it is very pure, not more than four grains. Boiling water dissolves half its weight. It is not altered by oxygen gas. The mineral, or the other vegetable acids, have little action on it, and do not com pletely dissolve it, especially when it is not quite pure. Alcohol developer in it an aromatic odour.
Suberic acid unites easily with the alka lies and earths. Its salts are named sube rates. The mineral acids in general preci pitate the suberic acid from their solu tions ; and they are decomposed by solu tions of almost all the metallic salts. Suberic acid has no action on platina, gold, or nickle ; but it forms .salts with the greater number of the other metals. In general, these salts do not crystallize, and they have a tendency to form with an excess of acid. Its action on some metal lic solutions give some appearances which may serve to diptinguish it. It deem= poses acetite and nitrate of lead, and ni trates of mercury and silver : with nitrate of copper it forms no precipitate, but the blue colour of the solution passes to green, as does also that of sulphate of copper : the solution of sulphate of iron becomes of a deep yellow, and that of sulphate of zinc of a clear golden yel low. A character peculiar to it is, that when a few drops of it are added to a so lution of indigo in sulphuric acid, it causes the blue colour to pass to a green.
The characters by which it is distin guished from the known vegetable acids are,I. from the citric, by not crystallizing; 2. from the gallic, by not precipitating iron back ; i. from the mallic, by being obtained in a concrete form ; 4. from the tartaric, by its volatility.; 5. from the oxa lic, by not precipitating the solution of sulphate of copper, and by yielding to it Lime. From these, and the various phe nomena presented in its combinations, it is considered as different from all the other acids.