The announcement that the new experiment in co-operative housekeeping now on trial at Salem, Mass., has brought the Norwegian cooking apparatus into use as a means of transporting dinners, " all hot," from the co-operative kitchen to the respective co-operative tables of those who have joined in the experiment, has attracted special notice to this useful implement. We gave a short notice of this device on page 346, Vol. XIX., but as many of our present readers may not have seen it, and much inquiry is now being made in regard to it, we will, at the risk of repeating ourselves to some extent, give an illustration and a more detailed description of the apparatus. It is constructed in the most simple manner, of a wooden box lined with four inches of felt, in which the saucepanscon-taining the food, previously boiled and maintained at the boiling point for five or ten minutes, according to the nature of the food to be cooked, are placed. The heated saucepans are covered with a thick felt cover, and, the lid of the box being fastened down, the rest of the cooking is done by slow digestion, no more heat being added. The heated vessels containing the food will retain a high temperature for several hours, so that a dinner put into the apparatus at eight o'clock in the morning would be quite hot and ready by five in the afternoon, and would keep hot up to ten or twelve at night, because the felt clothing so completely prevents the escape of the heat; and as the whole is inclosed in a box, there are no currents of air to Jcarry off any other heat by convection. A is the box, lined with felt; B B the saucepans fitting into the box ; C the felt cover, to be placed on the top of the saucepans. The principle on which this cooking apparatus acts is that of retaining the heat; aid it consists of a heat-retainer or isolating apparatus, shajed somewhat like a refrigerator, and of one or more saucepais, or other cooking vessels, made to fit into it. Whereas, in the ordinary way of cooking, the fire is necessarily kept up diring the whole of the time required for completing the cooiing process, tie same result is obtained, in using this apparatus, by simply giving the food a start of a few minutes' wiling, the rest of the cooking being completed by itself in the heat-retainer away from the fire altogether. DIRECTIONS POK USS.—Put the food intended for cooking, with the water or othet fluid cold, into the saucepan, and place it on the fire. Make it boil, and when on the point of boiling skim if required. This done, replace the lid of the saucepan firmly, and let it continue boiling for a few minutes. After the expiration of these few minutes, take the saucepan off the fire and place it immediately into the isolating apparatus, cover it carefully with the cushion, and fasten the lid of the apparatus firmly down. In this state the cooking process will complete itself without fail. By no means let (he apparatus be opened during the time required for cooking the food. The length of time which the different dishes should remain in the isolating apparatus varies according to their nature. It may, however, be taken as a general rule that the same time is required to complete the cooking in the apparatus as in the ordinary way on a slow fire. The advantages of this apparatus are thus detailed by Herr So'rensen, the patentee, whose attention was first directed to the subject by the Norwegian peasants, who heat their food in the morning, and while away in the fields keep the saucepan hot by surrounding it with chopped hay : 1. Economy ofMiel.—Varies according to thelength of time required for cook -ing the different sorts of food. For those requiring, in the ordinary way, only one hour's cooking, the saving is abovit 40 per cent ; two hours, 60 per cent ; three hours, 65 per cent; six hours, 70 per cent. In the caseof gas being used, the saving would-be greater still. 2. Economy of Labor.-r-A few minutes' boiling is sufficient. No fire is necessary afterward. The cooking pot once in the apparatus, the cooking will complete itself. Over-cooking is simply impossible, and the process of cooking is infallible in its result. The food will be cooked in about the same time as if fire had been continuously used But the food need not be eaten for many hours after the cooking process is complete ; so that half-an-hour's use of a fire on a Saturday night, for example, will give a smoking hot dinner on Sunday. 3. Portability.—The weight of the apparatus, complete, varies from 18 to 50 lbs. The apparatus can, in proportion to its dimensions, be carried about with great facility, without interfering with the cooking process. By means of a large apparatus—for instance, following on a cart a detachment of soldiers on the march—it is possible to provide them with a hot meal at any moment it might be found convenient (as may be proved by official reports from the officers of the Royal Guard at Stockholm, in the possession of the patentee). Again, fishermen, pilots, and others whose small vessels are not generally so constructed as to enable them to procure hot food while at sea, may easily do so by taking out with them in the morning an apparatus prepared before their departure. It is, in short, a thing for the million, for rich and poor; for the domestic kitchen, as well as for persons away from their homes. It cooks and keeps food hot, just as well when carried about on a pack-saddle, on a cart, or in a fisherman's boat, as in a coal-pit or under the kitchen table. 4. Quality and Quantity of the Mod Prepared.—Where other plans of cooking waste one pound of meat, this apparatus, properly used, wastes about one ounce. The unanimous testimony of those who have used it pronounces the flavor of food cooked in this manner incomparably superior to that which is ordinarily produced. 5. /Simplicity of Use.—One of the greatest advantages of this invention is, no doubt, its simplicity and practical application. There is no complication of hot-water or air pipes to retain the heat, no mechanical combination whatever for producing a high degree of heat by steam pressure; consequently there is no necessity for steam valves or other combinations which would render the use of the apparatus difficult and dangerous. Any person will, without difficulty, be able to use the apparatus to advantage after once having witnessed it in operation. No special arrangement is required in the kitchen for using the apparatus. Any fuel will do for starting the cooking. 6. In addition to all these advantages, the complete appai-ratus constitutes the " Simple Refrigerator " for the preservation of ice, which has attracted so much notice, and had such warm approval from medical men. It will keep ice in small quantities for many days.