Where bituminous coal is used as a fuel to generate power, for steam engines or other purposes, much of the carbon, of a volatile character, is carried off and left to settle down through the atmosphere, to the annoyance of everybody in its vicinity and to the direct loss of the consumer. For want of legal enactments, such as exist in England, some of our towns and cities are rendered unpleasant to their inhabitants and unattractive to strangers. The unconsumed carbon, which vitiates the atmosphere, where bituminous coal is the fuel, is neither healthy nor comfortable. The object of the device shown in the accompanying engraving is to provide for the complete and entire combustion of the gases and of the volatile, but solid particles of fuel, usually carried off by the draft to be deposited in a solid form. Fig. 1 is a vertical longitudinal representation of a furnace I and boiler, and Fig. 2 is a cross section, taken on a transverse line at the rear of the grate. Similar letters refer to similar parts in both engravings. The furnace is of the ordinary . style, its back, however, being an upright plate fitting the j convexity of the boiler and the level of the grate, and having an opening of an elliptical form, but curved on its upper surface, to the circumferential line of the boiler. Another upright plate, similarly formed, is placed just behind the first, having a similar projection. These are seen in both figures : s A is the boiler in Fig. 1 extending to the horizontal dotted j line, and in Fig. 2 being shown in transverse section. B, in Fig. 1, shows the sections of. the plates. The same in both figures show the form of the plates ; and, in Fig. 2, at C, the whole contour of the openings is shown, also in section in Fig. 1, same letter C. The gases of combustion are met at a point between the two plates by a column of atmospheric air (oxygen) admitted through side apertures seen plainly at D Fig. 2 to the space between the plates, B. It is evident that the outer air passing into the chamber, formed by the space between the two plates, and meeting the heated gases, smoke, etc., from the furnace, is at once expanded and intimately mixed with these products of combustion ; not passing through the opening in the rear plate in a direct line, but deflected against the surface of the plate, and thus receiving a recoil or revolution before passing off with the draft. Thus perfect combustion is assured, and an intense heat results, that passes along the bottom of the boiler and envelops its sides. The inventor believes that not only is the smoke all consumed, but that the power of the heat and, consequently, the economic use of the fuel are increased twenty per cent. Where, as on vessels, the bulk and weight of the fuel carried are important elements in calculating the capacity of a ship, the advantage of such a device is apparent; and also where the cost of the fuel is an important item. This improvement may bo applied to any ordinary furnace as well as to those built specially for its reception. The inventor and patentee guarantees that the improvement will accomplish all "that he claims, and invites those who desire further information to address J* L. Paige, No. 7 Howell street, Rochester, N. Y. Treating Textile Fabrics. M. Pierre Armand Neuman, of St. Denis, Paris, treats textile fabrics with sulphuric acid, for the purpose of rendering them impermeable. By this process the fibers on the surface of the fabric are partially dissolved, and converted into a glutinous substance, without the fibers in the body of the fabric being destroyed. The fabric, after being passed through the sulphuric acid, is quickly washed and rinsed in water, to stop the action of the acid, and remove all traces of it, and it is afterwards dried, when the part which has been acted on by the acid, having impregnated and coated the fibers of the fab-j ric, and filled up the interstices between the warp and the j weft, will convert it into a parchment-like and impermeable I materiel. .------------------~ m +~------------------ Heat and Steam. j A correspondent writing to us on the subject of " Waste and Economy of Fuel," seems to misapprehend Joule and Tyndall. One cubic foot of water when transformed into steam, does not, as he supposes, only contain 1,169 units of heat, but contains 1,169 multiplied by 62 pounds, or 73,062*5 units. The steam engine furnishes a ready and convenient method of determining the mechanical equivalent of a unit of heat, and shows conclusively, we think, that Joule's figure is too low. If we accept the results of the most careful physicists of our day, we may take the calorific value of one pound of good coal as equal to 7,500 Centigrade degrees. Two such pounds consumed in as perfect a steam engine as we can construct, gives us an indicated horse power of 33,000 foot-pounds per hour, so that twice 7,500 units, or 15,000, in this case, will produce in an hour an effect equivalent to 33,000 X 60 minutes, or 1,980,000 foot-pounds. One unit at atmospheric pressure of 14*706 pounds will then represent 132 foot-pounds. Reducing the pressure to zero, we obtain the equivalent of 1,931*192 foot-pounds for each unit of heat. Had the calorific power of 1 pound of coal been 6,000 units of heat, our equivalent would have been 1,838-25; if 8,000 deg., 2,426*32. The average would be 2,065 foot-pounds. This result we practically obtain every day with engines which we know to lose 30 per cent of useful heat. Adding this 30 per cent to our equivalent, as above, we obtain 2,684*5 foot-pounds, as the real equivalent of one unit of heat as exhibited by the working of the modern steam engine.