An instrument for permitting or arresting the flow of a liquid at pleasure. They generally consist of a short tube communicating with the cask containing the liquid, and having a plug ground into it near the middle, and standing at right angles to it. This plug has a hole through it, which being brought to coincide with the bore of the pipe, the plug offers no obstruction to the liquid, but by turning the plug one quarter round, the solid part of the plug stands across the bore of the pipe, and stops the passage of the liquid. Numerous peculiarities are to be found in the construction of cocks, to adapt them to particular uses; some of these we shall proceed to notice.

Cock 367

The annexed figure represents in section, an improved lock-cock for liquor-casks, invented by Mr. W. Russel. Numerous patents have been taken out for lock-cocks; but few of these inventions, we think, are equal to Mr. Russel's for simplicity and security. The engraving represents the cock shut-and locked. A square hole being cut through the barrel and into the plug a, a movable steady pin or bolt b, with a shoulder to limit its action, is fitted into it, passing through the barrel into the plug; the opposite end terminates in a screw, over which is a spiral spring resting on the shoulder; a turned brass socket c, having also a shoulder about midway to press upon the spiral spring, is then put over all, and secured to the barrel either by solder or screws; if by the latter only, the notches in the heads must be filed away for obvious reasons. To open the cock, or rather to withdraw the bolt, the screwed socket key must be introduced, when about two turns will sufficiently compress the spring and withdraw the bolt, and the cock may then be opened and shut at discretion, while the screw-key remains in the position described.

When the key is withdrawn, the action of the spring upon the plug forces the bolt into the aperture of the plug upon shutting the cock.

Cock 368

The accompanying figures represent another contrivance of Mr, Russel's, which he has named a " hydro-pneumatic liquor-cock, and air-vent attached,"the object of which if to admit the air to press upon the surface of the liquor, so as to cause it to flow upon opening the cock, but to shut off all communication between the atmosphere and the interior of the vessel when the cock is closed, by which the strength of the liquor is preserved, and it is prevented from speedily turning sour. Fig. 1 is a view of the cock with the air tube applied externally. The plug, in addition to the aperture for the passage of Fig. 1 the liquor, has a smaller one placed above it for the transmission of the Air: upon turning the cock to draw off, the air enters the smaller passage, and passing along the bent tube b enters the vat above the surface of the liquor through the metal plug or ferrule d. Fig. 2 is a section of a barrel showing another modification of the apparatus, by which the air-tube is placed internally; this method is considered preferable in brewers' or distillers' large vessels, and in situations where the tube, if applied externally, would be liable to injury.

Letters abed and e apply to the same parts as in Fig. 1; but the aperture for the admission of air in this cock is situated at the side (at e), in order to show the application of the invention to one of Mr. Russel's lock-cocks, already described.

Cock 369

The following cut represents a cock of simple construction, in which there is no plug requiring grinding into its seat, and which may be entirely formed of c;ist iron, which is at once cheaper and not pernicious like brass, a is the Fig. 2 barrel; b a small rod having a screw cut on the end g, which works in a corresponding screw cut in the nose of the cock; the other end of the rod passes through a guide-piece e (perforated with numerous holes, to allow an easy passage to the liquor), and through a leather washer, at the back of which is an iron washer, against which the rod is rivetted; and according to the direction in which the screw is turned, the leather washer is either pressed against the end of the cock, thereby closing the aperture, or it recedes from it, and opens the passage, f f is a section of the cask into which the cock is screwed. Another cock, in some respects resembling the preceding, but requiring greater accuracy of workmanship, is shown in the following figure, a is the barrel, bored out cylindrical, and the interior end faced or filed square; b the nozzle; c a conical plug formed upon one end of a screw; d a handle upon the other end of the screw, by turning which the plug may be made to close the cylindrical passage a, but when drawn back to the fullest extent, it leaves a clear passage for the liquor.

A great objection to metallic cocks is their liability to corrosion in liquors containing any portion of acid, by which means the plug becomes loose in its seat, and in many instances a poisonous solution of the metal is formed in the liquor. These evils are avoided in Ridgway's porcelain cocks, which are not liable to corrosion in the strongest acids, at the same time they are very firm and substantial, being formed of the strongest porcelain or stone ware.

Cock 370Cock 371Cock 372

The forms of the cock are somewhat new, as well as the interior construction. The annexed diagram gives a section (excepting the upper or handle part of the plug,) of the form most approved by the patentees, a is the long tube, with a screw thread cut upon its external surface for the purpose of being screwed into the barrel; b the plug accurately ground, and fitted into its place; in the plug a vertical perforation is made by boring, equal to the diameter of that in the long tube, and another hole at right angles to the former to communicate with the vertical perforation and with the long tube, when the plug is turned in the direction shown, for drawing off the liquor. To secure the plug in its place, and to produce a uniform action, it has a groove made three-quarters round it, for receiving the end of the bolt c which is fastened by the screw d. See Valves.