GREASE. Various kinds of tallow, fat, dripping, and kitchen-stuff receive the general name of grease, as applied to several manufacturing processes; but the name is now more technically given to the lubricating unguent employed for the rolling-stock of railway companies. While oil is the lubricator for the delicate parts of the locomo tive, grease is necessary for the axles of the wheels. So vast is the quantity used, that the annual demand amounts to thousands of tons; and, as the quality is very impor tant, most of the great companies make their own—establishing a marked distinction between the two kinds used for locomotives and for wagons.
Locomotive grease usually consists of tallow, oil, carbonate of soda, and water. Much depends on the consistency. If the grease is too thick, the axle-boxes become hot; if too thin, it is used up too quickly. Again, if there is too much alkali, there is a residue left in the boxes; if too little, the grease is too soft and wasteful. The grease is always yellow; but it is made of a thinner consistency for cold weather than for hot. The following are given as the constituents of two kinds that meet with approval, to produce one ton of each kind of grease, allowing a certain percentage for waste: The manufacture is very simple. The tallow and oils are heated to 180° F.; the water
and alkali to 200'; both are run off into wooden tubs, where they are well stirred till cold, with special precautions against the admission of any grit or dirt.
Wagon grease is coarser and cheaper in quality. The ingredients are chiefly some kind of resinous oil and caustic lime. When resin was cheap, wagon grease cost about half the price of locomotive grease, and was useful not only for wagon and carriage axles, but also for low-speed goods and mineral locomotives; but during the American war, the price of resin rose, and then attempts were made to use residues from parafline, -coal-tar, candle-making, cotton-seed oil, fish-oil, pitch-oil, and other substitutes.
It is said that 3,000 tons of grease are made every year in the Tyne district, not exactly as a primary product, but as using up a residue from the distillation of resin.