BROWN BROTHERS of Chicago have for the last ten years been active in the manufacture and sale of the patent sidewalk lights, and there is scarcely a city of any pretensions in the Great West that has not awaked up to the use and value of this most beneficial invention, and the pleasing consequence is that the Messrs. B. are now doing an immense business in the manufacture of them, at 226 and 228 Monroe street, Chicago, where the orders of our friends the Architects and Builders who propagate improvements in the growing cities of the irrepressible West, will be attended to, with that promptitude which has hitherto made the name of the firm of BROWN BROTHERS so well known, and their excellent manufacture so fully appreciated. WHITE LEAD BY A NEW PROCESS. The manufacture of this important and useful pigment has been very successfully prosecuted within the past year, by a new process, the invention of Dr. H. Hannen of this city, and is destined to supersede the old method, both as regards economy in preparation and purity of material. The old or Dutch process, requiring some six to eight months for its completion, fit for painter’s use; while by the Hannen patent it can be produced in from ten to fifteen days. The quality of the article is said to be fully equal, if not superior, to that of the lead made by the old method. The process of manufacture, as far as we can learn, is as follows: The best Spanish pig lead is melted in a large iron kettle, holding from fifteen to eighteen hundred weight, and then drawn off by a suitable valve, and allowed to run over a cast-iron wheel or drum, about six inches on the face and three feet in diameter, running at a high speed, and kept cool by a stream of cold water constantly playing on it. The lead, in passing over this wheel, is cast into ribbons about the thickness of paper, it is then taken and placed on lattice shelving in rooms some eight to ten feet square, made almost airtight by a double thickness of boards, and capable of holding some three tons of the metallic lead as it comes from the casting machine in ribbon form, the temperature of the room is then raised by injecting steam to about one hundred degrees, and then sprinkled several times a day with diluted acetic acid, converting it into sub-acetate or sugar of lead. While this operation is going on, carbonic acid gas is forced into the room by means of a blower or pump, which decomposes the acetate and forms a carbonate of lead; this operation of forming an acetate, and then a carbonate, requires from five to six days, until a complete corrosion of the lead is effected; the room is now allowed to cool and the lead to dry, after which it is taken out and sifted through fine wire sieves, which separates all undecomposed lead or other impurities. It is then ready for washing and drying. The finely powdered lead is mixed with water into a thick pasty form and ground in a mill of similar construction to an ordinary flour mill, from which