Of this mixture four parts are taken to one of zircon, thoroughly mixed, and melted in a platinum crucible at a red heat. The mass fuses readily, froths at first and gives off bubbles of gas, and flows then quietly, forming a very fluid melt. If the zircon is finely ground, 15 minutes are sufficient for this operation. The loss of weight is 16 per cent., and is not notably increased on prolonged fusion. It corresponds approximately to the weight of the carbonic anhydride present in the potassium carbonate.
As pungent vapors are given off during fusion, the operation should be conducted under a draught hood. The activity of the mixture in attacking zircon appears from the following experiment: Two zircon crystals, each weighing ½ grm., were introduced into the melted mixture and subjected to prolonged heat. In a short time they decreased perceptibly in size; each of them broke up into two fragments, and within an hour they were entirely dissolved. The melted mass is poured upon a dry metal plate, and when congealed is thrown into water. It is at once intersected with a number of fissures, which facilitate pulverization. This process is the more necessary as the unbroken mass is very slowly attacked by water even on prolonged boiling. The powder is boiled in a large quantity of water so as to remove everything soluble. There is obtained a faintly alkaline solution and a sediment insoluble in water. From the filtrate alkalies throw down zirconium hydroxide, free from iron.
The portion insoluble in water is readily dissolved in hydrofluoric acid, and is converted into zircon potassium fluoride. The chief bulk of the zirconium is found in the aqueous solution in the state of double fluorides. The platinum crucible is not in the least attacked during melting. On the contrary, dirty platinum crucibles may be advantageously cleaned by melting in them a little of the above mentioned mixture.
If finely divided zircon is boiled for a long time with caustic lye, it is perceptibly attacked. It is very probable that in this manner zircon might be entirely dissolved under a pressure of 10 atmospheres.
Potassium borofluoride may be readily prepared from cryolite. Crucibles of nickel seem especially well adapted for the fusion of zircon in caustic alkalies.—Ber. Bœhm. Gesell. Wissenschaft; Chem. News.
A PROCESS FOR MAKING WROUGHT IRON DIRECT FROM THE ORE.[1]
The numerous direct processes which have been patented and brought before the iron masters of the world, differ materially from that now introduced by Mr. Wilson. After a careful examination of his process, I am convinced that Mr. Wilson has succeeded in producing good blooms from iron ore, and I think that I am able to point out theoretically the chief reasons of the success of his method.
Without going deeply into the history of the metal, I may mention the well known fact that wrought iron was extensively used in almost all quarters of the globe, before pig or cast iron was ever produced. Without entering into the details of the processes by which this wrought iron was made, it suffices for my present purpose to say that they were crude, wasteful, and expensive, so that they can be employed to-day only in a very few localities favored with good and cheap ore, fuel, and labor.
The construction of larger furnaces and the employment of higher temperatures led to the production of a highly carbonized, fusible metal, without any special design on the part of the manufacturers in producing it. This pig iron, however, could be used only for a few purposes for which metallic iron was needed; but it was produced cheaply and with little loss of metal, and the attempt to decarbonize this product and bring it into a state in which it could be hammered and welded was soon successfully made. This process of decarbonization, or some modification of it, has successfully held the field against all so-called, direct processes up to the present time. Why? Because the old fashioned bloomeries and Catalan forges could produce blooms only at a high cost, and because the new processes introduced failed to turn out good blooms. Those produced were invariably "red short," that is, they contained unreduced oxide of iron, which prevented the contact of the metallic particles, and rendered the welding together of these particles to form a solid bloom impossible.