HAT TO FIT EVERY HEAD —Andrew Fulton, of Glasgow, patentee.This improvement consists in adapting to hats, helmets, ind other coverings for the head, a flexible padded lining which adapts itself readily to the exact contour of the head of the wearer, ind thus secures a good fit, while it also ensures all the ease and comlort derivable from the wearing of an easy cap. The lining is held to the sides of the head by gentle springs ind does not come so close to the interior, but that a space is left at certain parts for the idmission of air for ventilation. [London Vlechanics Magazine. [We commend this subject to the attention of our hatters, it is an invention ot a most de--irable chaiacter, and tha hatter who first introduces such an improvement among us should, and no doubt would, receive a very liberal patronage. IMPROVED PROCESS FOR REFINING GOLD. A patent has been recently taken out by Mr. Petrie, of London, for an improvement in vhat is termed the "parting1' process by refiners, and which is said to promise very important results. The refiners alloy, consisting >t one part impure gold and three partssilver, granulated in the usual manner, is placed in a number of small cells or cylinders, placed upright on an incline, between two parallel rails, which may, if desired, form flues, whereby the cells are warmed while in action Hot nitric acid is kept continually dropping from a tap into the highest cell, and having passed through the mass of alloy, and through a false bottom, ascends on the other sii)e of a diaphragm, and overflows into the next cell; from thence it flows into all the cells in succession. From time to time the upper cell is removed, and another, containing fresh alloy, is placed at the bottom of the series, the whole being moved up the incline. By the time the nitric acid reaches the granular surfaces, and as each, cell is laised it comes constantly in contact with more energetic acid, until, on arriving at the top, and before removal, the whole is dissolved, and the gold left pure in a spongy state. There is also an arrangement for condensing the nitrous fumes, which are conducted by stoneware tubes through an apparatus called a gas collector into an oxidator. They are afterwards drawn off by pneumatic suction, are condensed into Iresh strong nitric acid, which flows out in a continuous stream for further condensation, or for immediate use. ARTIFICIAL BLOCKS FOR HYDRAULIC PURPOSESThe material called hydraulic lime, generally used for engineers work under wa-'er, is a silicate of lime, in a somewhat nascent state. A discovery has been made by M. Berard,of Paris, of a most valuable process tor manufacturing blocks for hydraulic purposes, and particularly submarine ones. The commonest argil is employed by the inventor, which is a silicate, with a base of alumina; a block of any required dimensions is, therefore, constructed ot unburnt bricks, taken !rom the field and stratified in layers, with the fuel on some piles of bricks forming a grating. An outer casing of unburnt bricks a short distance all round the block is filled wi'h charcoal dust, the fire is placed at the base of the block, it soon rises, and heats the mass to a temperature which will soften argil, the contractijn causes sinkings and vacancies, which must be filled up as they occur. When sufficiently burnt, the outer casings, which will then be burnt bricks, may be taken down, and the block removed to its destination, [t will be seen that blocks may be made of any shape or size, having no limit but the possibility of carriage; and, when the operation is properly conducted, the solidity of the substance is remarkable; it requiies great force to break them, iron instruments will not scratch the suriace, steel scarcely mark them ; and as concentrated nitric or sulphuric acid, or the most energetic alkaline solutions will not have the least effect on them, they will be indestructible under the action of sea or any other water. DESILVERIZATION OF LEAD BY ZINC.Dr. Karsten, a German chemist, several years ago made some experiments with lead and zinc, and found that when a mixture of these metals was allowed to cool very gradually, lead with a minute trace of zinc was found at the bottom of the crucible, and zinc with a small amount of silver at the top. If the lead contained silver, it was almost entirely transferred to the zinc. Hearing that in Carmarthen silver is withdrawn from lead by means ol zinc, he resumed his examination of the subject. He found that silver may be entirely separated from lead by zinc, and that the following method gives the best results :A tube ot cast-iron 1J inch in diameter is fitted to the cru'ible, so that the desilverized lead may be let off from the bottom. One end of this tube, dipping nearly to the bottom of the crucible, i-furiiished with a slide moving in grooves at the edge of the crucible, so that it can be shu1 when required by means of a rod. In this way the stream of melted lead maybe regu lated, and the fall of level gradual and uni form, lu the crucible were put 25 cwts. of lead, containing seven eighths of an ounce 01 silver to the cwt,and4 cwt. of zinc. The whole was then fused, and stirred together for one hour at a bright red heat. This large amount of zinc was used because it was in-intended to attempt a process of concentration in which the same quantity of zinc should serve to desilverize subsequent charges of lead. After the stirring apparatus was withdrawn, and the melted mass kept for four hours at a red heat, the lead, perfectly freed from silver, was drawn off until only about 6 cwts. of metal remained in the crucible. To this residue a second 25 cwt. of zinc were likewise added, for reasons given below. A fourth, fifth, and sixth charge of lead were introduced and treated in like manner, 2 cwt. of zinc having again been added to the fourth charge. The lead drawn off, in each case, was entirely freed from silver. But when a seventh charge was introduced without an addition of zinc, the lead, when drawn off, still retained silver to an extent of jths of an ounce to the cwt. The desilveriz ing of 150 cwt. of lead in this manner requires 8 cwt. or 5 per cent, of zinc, a quantity differing widely from that indicated by former experimentsnamely, 1J per cent. An addition of 1 per cent, of zinc is quite sufficient for the perfect desilverization of lead when only one charge is worked. Thus 25 cwt. of lead may very well be freed Irom silver 42 lbs. of zinc, but the difficulty of separating the small quantity of argentiterous metal from the desilverized zinc is so great that this pbn is not practicable. On the other hand, there is a certain limit to the size of the crucible, which cannot be exceeded, and recourse must, therefore, be had, to a process of concentration. The silver is separated from the lead very imperfectly, if twice or thrice as much zinc as is required for one charge of lead is added at once, with the view of making it serve for several charges. It is likewise imperfect when, on introducing into the crucible the several charges of lead, the li per cent, needed for delivering the lead is added with each charge. It, therefore, with reference to the above exam pie, the first melting is made with 25 cwt. of lead, and 42 lbs. of zi c, the second, third, fourth, c, charges (added to the residue in the crucible) must also consist of 25 cwt. of lead and 42 lbs. of zinc. The cause of the unfavorable result of the process attempted by the author lies in the necessity for stirring the melted metals The oxidation of the lead and zinc at the sur tace of the mass is very disadvantageous. The argentiferous zinc obtained by this process always retains a portion of lead sufficient for the refining of the silver afer the zinc has been separated from the mixture; and the alloy of silver and lead remains in the distillation muffle. If the per centage of lead is not sufficient for this purpose, more must be added, in order that in the distillation vessels the silver may be accumulated in the lead, which is afterwards cupelled. The distillation does not present any difficulties when suitable muffles are emplojed. The author had muffles constructed which, except a slit of an inch in diameter, were quite closed for a height of 4 inches from the bottom. The slit could be closed and re-opened in the usual manner, when the distillation being completed, it was necessary to draw off the remainining argentiferous lead. Such a muffle was charged for each distillation with 1 cwt. of the metallic alloy of zine, lead, and silver. The product of fjur distillations of a mixture which, according to the most careful assays, contained M oz. of silver, was 242 lbs. ot lead and 44 9-44 o( silver. The loss of silver amounted, I herefore, to 3 1-22 oz.; this is owing chiefly to the scattering of srrull globules in the muffle, and it partly remains in the scum, from which it may be again recovered by subsequent distillations, washings, c. To COAT IRON WITH TIN.The tin is first melted, with a stratum of chloride of zinc and sal ammoniac on its suiface, and the iron or metal to be coated is immersed in the molten metal until sufficiently covered.
This article was originally published with the title "Recent Foreign Inventions"