the same way, by dissolving wrought-iron in molten copper. The results showed many discrepancies, because the amount of iron dissolved in each sample was far from uniform. He then tried to find a method by which he might be enabled to introduce a known and definite quantity of iron, and succeeded by dissolving iron in molten zinc to saturation, and adding the same, with or without pure zinc, to the molten copper. But when the metals were remelted, oxidation took place, and the castings again varied in character, owing to the oxides thus formed dissolving in the alloy, and diminishing its strength and toughness. This second difficulty was overcome by adding a small percentage of phosphorus in combination with copper. In some cases Mr. Dick also introduces tin, manganese, or lead into the alloy, to impart special properties to it. The various alloys thus produced are now manufactured and sold under the name of "delta"-metal. The inventor claims that by his process the iron is chemically combined in the brass and bronze, as proved by the alloys not rusting when exposed to moist air, and by their indifference to the magnetic needle. In a lecture by Mr. Macintyre before the Balloon Society on 15th November 1889, he states that "the properties which are combined in delta-metal- great strength and toughness, durability, resistance to corrosion, and a comparatively low price-render it of the greatest value for purposes of construction generally; and more especially for shipbuilding, marine engineering, and sanitary work. It can be equally well cast as forged, stamped and rolled hot, and drawn cold." The power of delta-metal to resist corrosion by the acid liquors of mines has been proved by the Bonifacius Coal Mining Company of Westphalia. The Company made a series of experiments with a view to finding the relative corrosion of metals of suitable strength. Brass and gun-metal were not strong enough, and trials were made with steel, iron, and delta-metal. Rolled bars of each of these were immersed during a period of six and a half months in the water issuing from the pits at Kray, and then carefully re-weighed and photographed. The bars were 7 sectional area of 62 square inches. inches long, and had a The following were the weights of the three kinds of bars before and after the trial: In the Schweizerisches Gewerbeblatt of 8th June 1889 the following tests of delta-metal were recorded: "In the first locomotive engines of the Pilatus mountain railway, a material was required which could be cast, and possess at the same time great tensile strength and elasticity. Delta-metal was found to answer these requirements; the worm-wheels of the brake gear for the engines were of this material and worked very satisfactorily. The castings were tested by Professor Tetmayer of Zürich, the results showing a tensile strength of 21 to 23 tons per square inch, with an elongation of 30 to 40 per cent on a length of 77 inches." Captain Locher also had the following tests made: One of the delta-metal pinions having been in use for a long time, the teeth had worn about of an inch, so that their thickness at the root was inch, and at the top inch, by a breadth of 47 inches. It was tested to show what power would be required to break such a tooth. The test, made by Professor Tetmayer, gave the following result :— P. AL P. 1 32 5 9 10 12 14 15 16 17 18 0 0.015 0.019 0.059 0.098 0.133 0.169 0.208 0.244 19 20 21 21 AL 0.295 0.354 0.472 | broke. P indicating the stress in tons, and AL the shortening in decimals of an inch of the distance L originally measuring 22 inch. Both as regards P and AL the results were unexpectedly favourable. The following test of delta - metal (forging) was made at Lloyds Proving House, Cardiff: The stalk of a valve spindle cast delta- metal billet, was cut below: -inch diameter at small end, drawn out of a 2-inch chill from the forging, and tested with results as per copy (The sample was reduced in centre for testing.) WHITE BRASS § 44. Alloys of copper and zinc containing less than 45 per cent of copper cease to have a yellow colour. The alloys containing from 40 down to 30 per cent of copper are silver-white, and with less than 30 per cent of copper the colour passes from gray to bluish-gray, having a greater resemblance to metallic zinc as the proportion of that metal is increased. The silver-white alloys break with a conchoidal fracture, and the more zinciferous alloys with a fracture more or less crystalline. In consequence of the brittle nature of white alloys they cannot be used for rolling and wire drawing, but some of them are used for pressed work, when too strong a pressure is not required. Some of them are known by special names, thus :— § 45. Birmingham Platinum and Platinum Lead are used for certain castings, but the composition is variable, according to the taste of the manufacturer. The following will illustrate this point :— The above alloys are used for buttons by casting them in moulds giving sharp impressions, the letter or crest being subsequently brought out by careful pressing. Other alloys for buttons consist of— § 46. Sorel's Alloys.-These alloys are distinguished by great hardness and considerable tenacity. They cast well and can readily be detached from the mould. They are largely used for statuettes and other artistic work, which, after suitable bronzing, are brought into commerce as castbronze. The following mixtures are recommended : |