The losses by fire in the United States, from last January to October, in-elusive, amount to the large sum of $33,0S4,OO. M. Delaurier states that oxygen may be obtained very eeonomically from manganate of lime, as tnls salt when heated gives off that gas very abundantly. A surveying party of the Ban Diego, EI Paso , and Memphis Railroad have passed the summit of the range of mountains between San Diego and Fort Yuma. They report the grade to be less tlian 100 feet per mile. A writer in Comptes Rendus says that if articles made of copper be Immersed in molten sulphur having lamp-black in suspension, they assume the appearance of bronze, and ean be polished without losing that aspec*. It is stated that Mr. A. T. Stewart has purchased the block lying between North Twelfth and North Thirteenth streets, and First street and the East river, Brooklyn, for $200,000, .and that he intends to -build thereon a depot for the proposed railway to Iilempstead. Water collected from roofs or kept in tanks covered with zinc has been found by M. Zuirck to be so much contaminated by that metal as to prove detrimental to health, when used for domestic or industrial pnrposM, He recommends that such tanks or roofs be painted with asphalte varnish. Chicago i8 going into the iron manufacture on a large scale, and with .Lake Superior ores. A number of capitalists there have formed a company and contemplate the erection of a large mill at Joliet. Wrougkt Iron gas and water pipes will form one feature in the production of the es-tabUshment. The miners of thejWilkesbarre (Pennsylvania) Coal and Iron Company have a fund of five thousand dollars for the use of those of tkelr number who may be disabled in any way. It was raised by each miner and the company giving the earnings of one day ; one thousand dollars is to go to Avondale,and the balance in the above manner. The Dariencanal project is reviving. The UnitedJltates steamer NIpsic, attached to the South Atlantic squadron, is under orders to proceed to the Isthmus of Darien to make surveys and explorations,with a view to determine the best location for an inter-oceanic canal. A similar survey on the Paciflc shore of the Isthmus will be made at a future day. It is asserted that President Grant will recommend the early construction of this Darien ship canal in his forthcoming message. What truth there may be In the statement it is ciUtHcult to say, as never before has a president beenso successful iJpreventing a premature pnbJcation of the contents "f the annual communication to Congress. M. Mne says that when woods of a naturally white color are pamted over with a concentrated aqueous solution of permanganate of potassa, they assume the appearance of walnut wood. Different woods behave in a different manner when acted upon by tins solution. The woods of the peai tree and the cherry tree are readily stained, while the white woods (the acacia, for example) resist a longer time, and resinous woods, as the fir, are still more difficult to affect. The rationale is that the permanganate of potassa is decomposed by the woody libers ; brown peroxide is precipitated and fixed by the potassa. which is afterwards removed by washing with water. The wood when dry is varnished, and is not easily distinguished from woods of a naturally dark color. Correspondents of the Olwmieal News give two methods of constructing foot-paths : (1.) One part of Portland cement mixed with seven or eight parts of gravel, or old, hard rubbish, such as brick-bats, broken stonee, etc., will make a neat. cheap, permanent garden walk, impervious to wet, and not readily affected by changes in the weather. (2.) A very good, and comparatively cheap foot-path may be made by laying down, first, a layer of coarsely broken-np old brlcKs, next, some middling coarse gravel, and over that a layer. from two to four inches in thickness, of small sea-shells-ICcare be taken tobest or roll the broken-up bricks aaidgravelinto a somewhat solid mass, the shell-covered surface may be advantageously rolled In with a heavy iron roller, and will form even on soft sub-soil, a durable and inexpensive roadway. GROOVED WHEEL KAILBOAD B-RAKE.-A novelty in railroad brakes, which seems to u/S to possess much merit, is the subjeet of a recent patent granted to R. d'Heureuse, whose address is Box New York. Grooved wheels are employed between the running wheels of the truck, raisedjust enough to clear the rails, when it is desired that the spaed be unimpeded; but when the motion is to be arrested or retarded, the grooved wheels are depressed upon the rails and the braike blocks forced down into the grooves, thus qmckly effecting the purpose. This system of brake is operated by either hand or steam power, gnd with but a small expenditure of force. A model exhibited at thelate American Institute Fair, worked well, and seemed to be a step in the direction of improvement. As the grooved wheels are arranged in the middle of the truck, the weight of the car would- be sustained by them, in the event of an ordinary running wheel or its axle being broken, and many of the accidents so frequently occurring would thus be prevented.