X84.8."] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



187 



ON FLAME AND GASES. 



Professor Faraday lately read a paper at the Knyal Institution, " On the 

 Siamagnetio Condilion of Flame and Gases."— Mr. Faraday having briefly 

 recapitulated the chief subjects of his recent research into tlie magnetic con- 

 dition of matter, proceeded to state a still more recent extension of these re- 

 searches made by Prof. Bancalari at Venice. Prof. Bancalari has shown that 

 iiame, when placed between the poles of a powerful magnet, becomes rfia- 

 magtielic {i. e. spreads out in the plane which is perpendicular to the line 

 joining the poles of tlie magnet). Prof. Faraday's object was — first, to re- 

 move certain misapprehensions of his own published opinions in regard to 

 this phenomenon ; and, secondly, to give a philosopliical account of it. Re- 

 ferring to his " Experimental Researches," in the Philusojihical Transactions, 

 read in 1845 (pars. 2123, 2433, 2435), he showed that lie had never asserted, 

 as had been ivoagined, that the gases were not subject to magnetic action ; 

 but merely that his experiments had not then established that they were 

 affected by that force. The causes of this magnetic influence were then 

 considered. Flame was dissected, and its complicated nature — consisting of 

 solid matter, of a surrounding film of heated air, and of gaseous products of 

 combustion — was experimentally demonstrated. The following experiments 

 were then exhibited to prove (a) that hot air is diamatjnetic with reference 

 io cold ait — (^) that carbonic acid gas, a product of comJntstion, is diamag- 

 netic — {c) that carl/on, which is liberated during combustion, and imparts 

 iuminosity to flame, is also diamagnetic. 



(a) Hot air is diamagnetic with reference to cold air. Tlte hot air rising 

 from a glowing spiral of platina wire, placed between the poles of a powerful 

 electro-magnet, was proved to be bent aside by the fact of its inflaming a 

 piece of phosphorus in the equatorial plane on either side of the red-hot 

 platinum while the magnet was active, and also by its not firing the phos- 

 phorus (as v\ould happen in the ordinary condition of things) when this 

 substance was placed immediately above the heated wire. 



(A) Carbonic acid gas is diamagnetic. This was proved by a jet of that 

 gas being made to diverge from the perpendicular downward current, which 

 its gravity would cause it to take, into a flask of limewater (which it rendered 

 turbid) placed in the equatorial plane. 



(c) Solid carbon is diamagnetic. It was shown that the smoke of a taper, 

 •when placed beneath the axial line, divided itself, as flame was made to 

 divide, into two streams in the equatorial plane, each on either side of this 

 axial line. 



The singular condition of oxygen gas, in being far less diamagnetic than 

 the other gases, and therefore appearing as if magnetic, like iron, when sur- 

 rounded by other gases or air, was demonstrated by its carrying a cloud of 

 muriate of ammonia (itself diamagnetic) to Ihe poles of the magnet, around 

 ■which it seemed to gyrate in vortices. 



. Mr. Faraday concluded by noticing the apparently exceptional case of 

 'flame penetrating the pierced poles of a magnet, and coming through them 

 .Ti an axial line. He showed that in this case the maximum of force was not 

 'n this line, but in the circle of lines forming the edges of the hollow cylin- 

 der drilled through the poles. Therefore — inasmuch as the force in the 

 Tacant space was feebler than the force at its solid circumference — flame, 

 which always goes away from the spot where the force is strongest to the 

 .spot where it is weakest, penetrated the hollow axis of the cylinder. 



PROCESSES FOR UNITING METALS AND METALLIC 

 ALLOYS. 



At a recent meelinj; of the Berlin Academy of Sciences, M. Pulbrich, 

 founder, of Hambursh, communicated an account of his processes for firmly 

 uniting metals or metallic alloys, which possess difl'erent properties and 

 values, such, for example, as bar-iron with cast-iron, gun-metal with cast- 

 iron, and thus to obtain pieces of mixed metal suitable to make clasps, 

 girders, panel squares, railway bearings, wheels, axle-trees, and other 

 parts made use of in machinery and in building, possessing the weight and 

 the cohesion required, but much harder and more resistent in certain 

 parts than inothers. The following is the process adopted, as described 

 by Ihe inventor : — 



" To Unite Bar-iron to Cast-iron. — In order to unite bar-iron to cast- 

 iron — to make, for instance a bar of rectangular girder, of which one- 

 fourth the thickness shall consist of bar-irou, and the three other parts of 

 cast-iron, or rather in the combination of o]ie volume of these metals in 

 any proportions, I proceed as follows :— I take a bar of iron, of the re- 

 quired thickness, and I plunge it into a cleaning bath composed of nitric 

 acid or any other acid diluted with water. 1 theu take it out of the 

 cleaning bath, expose it to a red heat in a furnace, and plunge it again 

 into the cleaning bath ; by means of these operations, I get rid of all Ihe 

 oxide from the surface of the meial. To' remove from this bar any acid 

 ■which might remain, I wash it with any alkaline solution (for instance, sal 

 ammoniac), and I immediately plunge it into a bath of melted tin, where 

 I allow it to remain until it has become well tinned over its whole surface. 

 This done, I apply to the tinned iron at the side where it is to be united 

 •with the cast-iron, an alloy or solder composed of copper and tin, in the 

 proportions of five parts of copper, and 95 of tin. The bar of iron thus 



prepared is then introduced to the bottom of a mould of (he form and 

 dmiensions corresponding to the bar which it is wished to be produced 

 and It IS kept down by iron bolls or nails, w hich have previously been 

 well tinned ; tlie cast iron is then poured in a liquid slate on the bar of 

 iron, until the mould is filled. In this slate, a fusion takes place at the 

 surface of the iron in contact with the liquid cast nielal, and under the 

 influence of the alloy of solder of copper or tiu interposed, Ihe two pieces 

 of bar-iron and cast-iron unile so firmly the one to the oilier, Ihat it is 

 almost impossible to separate them. 



''To Unite Sled with Cast-iron.— Follow exactly the same process as 

 above described. 



" To Unite Copper, Bronze, Gun-Melal,or Brass, with Cast /™«.— These 

 alloys, as well as all those of copper, can be uiiiled by exactly similar 

 means to those above described ; except Ihat instead of clearinL' the sur- 

 faces of the alloys by means of acid and alkaline solutions as above men- 

 tioned, the surfaces shoulil be filed, and lh» union with the cast-iron 

 elfecled at the lowest temperalure possible, iu order that the bar of alloy 

 might not be melted. 



" The proportion indicated above for the composition of the alloy or solder 

 is that which appears the most suitable, where ihe pieces of metal to be 

 united are of moderate dimensions; but when they exceed moderate di- 

 mensions, it will be better to increase the proportion of copper employed. 



" In the examples given above, it is supposed that the difl'erent metals 

 were united toselher on one side only ; but one of these metals may be 

 united at two sides, or at two opposite or adjacent faces, to the other 

 metals, or even covered throughout its entire surface. Further, the pieces 

 of nielal may have a curvilinear, angular, or any olher form, and the 

 mnianuer of ouldiug may be varied according to the rules which practics 

 has long since furnished in foundries." 



THE EFFECTS OF ZINC ON IRON. 



A letter from Mr. James Nasmyth, of Riidgewater Foundry, Patricroft 

 near Manchester, to the Mining Jonrnnl, communicates the results of some 

 experiments recently made at the desire of Ihe Lords of the Admiralty, 

 with a view to determine whether old iron that had been galvanised, or 

 coated with zinc, was rendered unfit for being again norked-up. The 

 results of these experiments seem to prove Ihat the quality of the iron 

 is improved instead of being deteriorated by the zinc combined with it. 

 The following is Jlr. Nasmjth's report of the experiments : — 



" A piece of galvanised iron-wire rope was welded up inloa bar,and put 

 Io the most se\ere test. In the first place it was found, Ihat although the 

 iron-wire was quite covered wiih metallic zinc, which, although partially 

 driven ofl" iu the process of welding, yet, so far from the presence of the 

 metal, or its oxide, presenting any impediment to the welding of Ihe iron 

 (as in the case of lead), the iron-wire welded with remarkable ease ; and 

 the result was, a bar of remarkably lough, silvery-grained iron, which 

 stood punching, splitting, twisting, and bending, in a manner such as to 

 show, that the iron was not only excellent, but, to all appearance, actually 

 improved in quality in a very important degree. 



" Encouraged by such a result, a still further, and even more severe, trial 

 was made — viz.: by welding up a pile of clippings of galvanized iron- 

 plates, or sheet-irou, covered with zinc, as in the former experiments. The 

 presence of the zinc appeared to oiler no impediment to the welding, and 

 the result was, a bloom or bar of iron — Ihe fracture of which presented a 

 most remarkable and beautiful silvery grain — as good, if not superior, in 

 aspect to the finest samples of ' Low Moor' or ' Bowling ' iron. Bloom 

 of this iron were rolled out in rods, and tested io the cable-proving 

 machine, and the result indicated from 5 to 10 per cent, higher slrength 

 than Ihe best samples of wroughl-iron — thus establishing the fact, that, so 

 far from the presence of zinc being destructive to the strength and tenacity 

 of vvrought-iron, the contrary is the case. 



" I may mention, that bars of iron were heated to a welding beat, pre- 

 pared by Scarf for sheathing, in the usual manner; and, on drawing them 

 from the fire, for being welded, a handful of zinc filings was thrown 

 on the welding hot surface, and the welding proceeded with. In this 

 severe test no apparent impediment to the process resulted ; the iron 

 ■welded as well as if no zinc had been present." 



Mr. Nasmyth infers from these experiments, that some improvement 

 might be made in the manufacture of iron, by the introduction of metallic 

 zinc in Ihe puddling furnace. In corroboratiou of this opinion, he adduces 

 the fact that the strongest cast-iron made in Belgium, and selected for 

 the casting of guns, is made from au iron ore in which the ore of zinc 

 forms a considerable portion. 



Mr. Leighton, of Owmammon, following up the suggestion of Mr. 

 Nasmyth, has communicated other applications of zinc to iron, which he 

 had devised for the purpose of bringing anthracite coal more into use. 

 His object was the preparation of pure oxide of zinc to be used as paint, 

 for iron-work more especially, for making joints, &c., in lieu of white- 

 lead." If," he observes, " people could be once induced to make a trial of 

 anthracite coal, worked by a blast, for several manufacturing operations, 

 the value of this peculiar fuel would be established. It only requires a 

 beginning ; it is quite possible to treat the sulphuret of zinc — a very 

 abundant ore, known as blende, or black jack — so that pure oxide of zioc 



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