When the so-called " anti-friction alloys," or " white metals," were introduced, reports as to their value soon made their appearance, and one of the most important was that of Nozo, the engineer of the repairing shops on the Northern Railroad of France. Nozo experimented with Grafton's, Vaucher's, Detourbet's, and other metals, and he arrived at the conclusion that the " white metals," whether for whole journals or their linings, might be advantageously employed in machinery revolving with a small velocity, or with an average velocity and small strain; but that they were not suited to the rolling stock of railways, in which the strains and the velocity are such as to rapidly wear all metals not hard enough to resist energetic friction. The term " white metal" is applied to all alloys in which zinc, tin, or lead is in sufficient proportion to impart a white colour, and a reference to the list on p. 34 will show that the number of white alloys is great. Babbit's metal and Parson's white brass are the two best known of these, but it may be doubted whether any hard and fast line as to the proportions of the respective ingredients can be drawn.

On the contrary, it would seem that brasses suitable for various kinds of work may be made almost haphazard, with just as great a probability of obtaining a good result as if the utmost care were taken in weighing the components of the alloy, and adding them in the proper order in the crucible. A good white metal for lining journal boxes, pillow-blocks, etc, is made of-

In this the thin is in excess, and the alloy is prepared in a roundabout way: 12 parts copper are first melted, and then 36 of tin are added; 24 of antimony are put in, and then 36 of tin, the temperature being lowered as soon as the copper is melted, in order not to oxidize the tin and antimony, the surface of the bath being protected from contact with the air. The alloy thus made is subsequently remelted in the proportion of 50 parts alloy to 100 tin. For small journals, where the friction is not great, both the copper and antimony may be doubled in quantity. An alloy of 1 part copper, 50 tin, and 5 antimony, has a greasy feel, and is good for machines not overworked; but a better metal for lining bearings subjected to rapid, not heavy friction, is made of 85 parts lead, 15 antimony. Vaucher's alloy is composed mainly of zinc and tin, with small quantities of lead and antimony, the last being melted separately. Brasses for locomotive bearings are usually made of-

But experiments recently made in the United States have yielded very good results with white metal for the journal-box linings of engines, coaches, and waggons. Babbitt's metal - the composition of which is variously stated-resembles the alloy first specified, and may be described as a tin alloy, 10 parts of that metal being used in conjunction with 1 each of copper and antimony. In recent years, phosphor bronze and manganese bronze have established a good reputation, and latterly cadmium has attracted some attention as an ingredient in alloys for bearings. It fuses below a red heat, and volatilizes so readily at the ordinary temperatures necessary for making alloys, that great difficulty has been experienced in using it as an ingredient. It is malleable and ductile, is harder and more tenacious than tin, but soils paper as lead does when it is rubbed over it. Possibly this property has attracted inventors to it, as the fine particles thus removed on slight friction Would probably produce a highly smooth surface on a bearing made of an alloy containing cadmium. In Lechesne's new white metal, the novel feature is the use of cadmium.

The proportions preferred are-

On different lines of railway, and in various countries, a very large number of alloys have been tried for bearings. Thus, where the freight is light, bearings made of an alloy of lead and antimony have been found to give good results - the life of the journal being prolonged at the expense of the bearing, and with an increased consumption of lubricant. Alloys of tin and copper have been tried; but, except in some few proportions, they are too hard; though when the tin preponderates and there is an addition of antimony, a good bearing is obtained, but at too high a price. Bearings of white metal, and of an alloy of antimony and lead, possess the advantage that they are easily replaced; but unless the supply of lubricant is kept up, they soon wear out, and the latter rapidly fuse if the journal becomes heated. White metal bearings, with the copper and antimony preponderating, are too hard, too brittle, and break under heavy loads; while, if the tin is in excess, and they are subjected to great pressure, they soon wear out of shape.

Dr. Kunzel, whose name is well known in connection with phosphor-bronze, has made many experiments on bearings, and concludes that for a bearing to possess all the required qualities it should be heterogeneous in constitution, and that its skeleton, so to speak, should be. made of a metal as tenacious as possible, the hardness of which is nearly equal to that of the journal, so as to enable it to resist the shocks to which it is subjected without changing its shape. The interstices or pores of the skeleton should contain a soft metal. The final result of Dr. Kunzel's investigations was the invention of his patented alloy (see p. 31), which consists of phosphor-bronze, with certain quantities of lead and tin added to form the soft alloy for filling the pores. By varying the proportions of the.ingredients, and by adding or omitting the proportion of zinc, the hardness of the bearing may be adapted to that of the journal. (Eng. Mech.)

Aich, Or Gedge's Metal

This is an alloy of zinc and copper in nearly the same proportions as in Muntz's metal, but it contains also a little iron, thus :-

It is very malleable at a red heat, and may be hammered, rolled, drawn into wire, or readily cast. It has been employed in Austria for casting cannon, and some Chinese cannon consist of a similar alloy.

Sterro-Metal

This is a very strong and elastic alloy used by Austrian engineers for hydraulic press pumps. It contains copper, zinc, iron and tin, in the following proportions:-

Good specimens offer far more resistance than gun-metal to transverse fracture, and cost only 2/3 the price. It is said to have been discovered in an attempt to employ, for the manufacture of brass, the alloy of iron and zinc found at the bottom of the zinc-pots in making galvanized iron.