Hot water and steam heating systems have their respective advantages. The furl cost is generally in fa-Tor of hot water, since the amount, of heat given off. by the radiator may he varied to suit the weather conditions by varying the water temperature; whereas, with steam, unless a vacuum system he used, the water must be raised to 212° K. before the radiators will he-come heated Further]more, some pressure must be generated in the system in order to drive out the air which collects in the radiators. With hot water the system is noi-eless, whereas with steam, unless both valveson each radiator are properly operated, water hammer will occur.
The name of Skagway. a prominent town in the early rush to the Yukon gold field, means " Home of the North Wind.*' The fare on the railroad from Skagway to White Horse-a distance of 112 miles-is $20) one way.
A large and fast locomotive, constructed at Munich, and now being exhibited at Nuremburg. is said to he capable of pulling a passenger train at the speed of 93 milesan hour. The German State Railway will shortly make experiments with the new locomotive for regular service on through routes.
Prof. Cha8. L. Norton, of the Institute of Technology, gives the heat unit of various kinds of fuel obtainable for one cent, as follow: Coal, $12 per ton,-23,000; wood, $10 per cord. 27,000; Oil. 12 cents per gallon, 15,000; coke, $10 per ton, 24,000; gas, $1 per 1000 cubic feet, 6500."
An acetylene blowpipe, in which oxygen is used with acetylene, has been invented. With its use a very high temperature is obtainable, owing to lheab-settce of inert nitrogen from the flame. It is claimed that with it a rod of pure iron serves as a soldering stick, and the heat is so great that a little of the carbon in the flame unites with the iron, converting it into mild steel.
To clean gas stove burners badly incrusted with grease, boil them in strong lye water or, in very bad Cases, heat them to the point of redness over a fire. In heating burners to clean them, extreme care must be used to prevent them overheating, or they will be ruined.
Mirrors are silvered with amalgams. The simplest of these is composed of one part tin and three of mer-CUiy. A better grade of amalgam consists of two parts bismuth, one each of lead and tin and four of mercu:y.
Recent experiments are said to have demonstrated that cadmium gives protective coatings for iron much superior to zinc, being much more adhesive and harder. Like zinc, it finally bec mes tarnished. but less rapidly. It withstands the effects of acid fumes better than zinc.
When driving out bolts, where you have no protection for the thread, strike the hardest blow you can give with a heavy hammer. Light blows with a small hammer will upset or rivet the bolt ends.
To prevent lamp chimneys from easily breaking, put them in a |>ot of cold water over the lire and add some common table salt. Boil well and let coul slowly, then take out the chimneys and wash them well.
A fraction of one per cent of sulphur destroys the malleability of iron when hot; while the presence of carbon lowers the fusing point by several hundred degrees.
A lubricant recommended for reamers by an American mechanic is a mixture of tallow and Hake graphite. With this lubricant, he says, any old, out of round, hand ground reamer works smoothly.
Amber varnish is amber heated with linseed or nut oil and thinned when cool with turpentine. It is insoluble, hard, tough, and of permanent color. It dries slowly and forms an excellent mixture with copal varnishes, making them hard and more durable.
A substitute for platinum for use in electrical appliances is a new alloy consisting of 161/2. ounces silver, 41/2 pomds nickel. 1/2 ounce bismuth and 53 pennyweights gold. The cost of these ingredients is approximately $73.55, while an equal quantity of platinum is worth $2102.83.
The alloy of gold with mercury is known as airal-gam. Mercury alloys with gold with great avidity, this being due not only to the marked affinity of the metals, but also to the fact that mercury is a metal which exists iu the molten state at an ordinary tem-perature.
The task of separating the diamonds from the blue-ground in South Africa requires months. From the shait the ore is conveyed to what are called the '•floors"-great stretches of ground cleaned off like a tennis court. The one is taken there in trucks or cars, which are fastened 10 leet ;apart to an endless cable, propelled by the power Horn the engine room. Each floor is 400 feet square, but their combined territory covers a great area of laud, one mine alone having " floors" which extend live mines.
These *' floors " are nothing more than the dumping grounds. Upon their smooth surface is spread the blueground to a depth of about 10 inches. Being very susceptible to the action of air and water, the blue-grouud disintegrates after being exposed six months and is beginning to become pulverized. The harrowing is done by steam plows drawn back and forth over the 'floors" by a cable. Any of the blueground that is not decomposed by the long exposure is taken to the crushing machine, where it is pulverized. AM the pulvertz.ng bluegroiind is taken to the pulsator or separating rooms.