The Chemistry of Cookery

from the meat from being overheated and filling the roaster with the fumes of burnt—_i.e._ partially decomposed, fat and gravy, to the tainting influence of which Rumford attributed the English prejudice against baked meat. So long as any water remains the dripping cannot be raised more than two or three degrees above 212°. [Illustration: FIG. 3.] [Illustration: FIG. 4.] The tube _v_, Fig. 1, is for carrying away vapour, if necessary. This tube may be opened or closed by means of a damper moved by the little handle shown on the right. The _heat_ of the roaster is regulated by means of the register _c_, Fig. 4, in the ash-pit door of the fire-place, its _dryness_ by the above-named damper of the steam tube _v_, and also by the blowpipes, _b p_. These are iron tubes, about 2½ in. in diameter, placed underneath, so as to be in the midst of the flame as it ascends from the fire into the enveloping flue, shown by the dotted lines, Fig. 4, where their external openings are shown at _b p_, _b p_, and the plugs by which they may be opened or closed in Fig. 1. It is evident that by removing these plugs, and opening the damper of the steam pipe, a blast of hot dry air will be delivered into the roaster at its back part, and it must pass forward to escape by the steam pipe. As these blowpipes are raised to a red heat when the fire is burning briskly, the temperature of this blast of air may be very high; with even a very moderate fire, sufficiently high to desiccate and spoil the meat if they were kept open during all the time of cooking. They are accordingly to be kept closed until the last stage of the roasting is reached; then the fire is urged by opening the ash-pit register, and when the blowpipes are about red-hot, their plugs are removed, and the steam-pipe damper is opened for a few minutes to brown the meat by means of the hot wind thus generated. It will