The acetic acid that accumulates in the boiler, C, must be again vaporized and treated until it no longer gives off any steam at all through the pipe, G. The amount of cooling water admitted into the worm, e, that traverses the head, D, is regulated according to the degree of concentration it is desired to give the acid. As soon as the steam can no longer be separated in the boiler, C, and temperature has reached 118 degrees, the anhydrous acetic acid is distilled through the tube, g, and received in the cooler, K, wherein it condenses. When the contents of the boiler, A, have been distilled to dryness, the tube, d, is closed and the cock of the tube, c, is opened. After this, steam is injected directly through the tube, k, in order to distill the acetic acid that still remains in the residuum, and which passes thus through the tube, e, into the worm, h, and flows into the two-necked bottle, S. There may be added to the boiler, C, certain materials for purifying the acetic acid, such as permanganate of potassa or acetate of soda, so as to obtain an absolutely pure article.--_Dingler's Polytech. Journal_. * * * * * FIELD KITCHENS. We illustrate the field kitchens of Captain J.C. Baxter, R.E., in the Inventions Exhibition. Figs. 1 to 3 represent Captain Baxter's Telescopic Kitchen, both open for use and packed up for traveling. These kitchens, which are on an entirely new principle, consist of from three to five annular kettles, either circular or elliptical, which are placed one on another, and the fire lighted inside the central tube. The kettles are built up on the top of the outer case in which they are carried, the central tube being placed over the grate in the lid. A small iron stand, supporting an ordinary pot, is placed on the top. When packed up, the annular kettles fit or nest into each other, and into the outer case; the iron stand packs inside the innermost kettle, and the top pot is placed on the outer case, being secured by a strap. This form of kitchen is intended for the use of officers, both regular and volunteer, and for officers' and sergeants' messes on active service or in camp. They are also suited for travelers, explorers, colonists, boating, shooting, and fishing parties, and in fact for all who may require to cook in the open air. Figs. 4 to 6 represent the kitchen of the field service pattern with conical kettles, while Figs. 7 and 8 represent the same pattern with elliptical kettles. These kitchens consist of five annular vessels, either circular or elliptical, which are placed one upon another, and the fire lighted in the central tube or flue. A small iron stand, supporting an ordinary pot or kettle, may be placed on the top as in the other set. A small hole, 18 inches long, 6 inches deep, and of the same width as the central tube of the annular kettles, may be made for an ashpit, or the kitchen may be raised a few inches from the ground on stones or turf.