attends its use as ordinarily employed, it is, that it is impossible to heat substances in it to the boiling point, for the water itself is only at that temperature, and the substance in the inner vessel is always a few degrees below. This evil may, however, be entirely obviated, by using a solution in the outer vessel, which boils at a higher temperature than 212°, and which will therefore raise the inner vessel and its contents to that point; thus, if the water be made to dissolve as much common salt as it is capable of doing, it will not boil until it is heated to 224°; or if it is saturated with sal-ammoniac or nitre, the heat will rise 12° or 14° higher. We need scarcely say that the first of these substances will be found a very useful and economical addition to the _bain marie_. When chemists require a still higher temperature, they have recourse to a bath of olive oil, which is capable of bearing a degree of heat as high as 500°; but its extreme danger over an open fire entirely precludes its use in any culinary operation. The mode of conducting the operation of boiling should not be uniform, but vary with the different purposes required. Thus, in the case of meat, a temperature of 212° hardens, instead of softening, two of the substances which it contains; namely, the fibrine, or material forming the chief part of the muscular fibre, and the albumen, or portion which is analogous to white of egg; if, on the contrary, meat is cooked by means of water at a lower temperature, the most nutritious parts are dissolved out, and the solid food left comparatively innutritious. The celebrated German chemist, Liebig, proposes the following plan:—he recommends that a piece of meat of considerable size should be taken and plunged into perfectly boiling water, over a good fire; that the water should be kept boiling for a few minutes, and then a portion of cold water, equal in quantity to about one-half of the boiling water, should be thrown in: this will reduce the temperature to about 160°, at which point the meat should be kept until thoroughly done; which, however, takes a much longer time than in the ordinary mode. The object of this mode of proceeding is, in the first instance, to harden the exterior of the meat, converting it into a sort of crust, which prevents the escape of the nutritious juices into the water, whilst the long continuance of the gentle heat afterwards cooks the interior without hardening either the albumen or the fibrine. Of course, where the object of boiling is to make soup, the opposite plan must be had recourse to; the meat should be in small instead of large pieces, put on in cold water and very slowly heated, so that all the soluble parts may be dissolved before the fibre is hardened by the action of boiling water.