Jan. 20, 1882. J 



* KNOWLEDGE 



255 



ALUMINIUM. 



[222] — Witli reference to query 157, I give the following method 

 "f extracting aluminium, as it maybe of general interest to your 

 readers of Knowledge : — 



A miitnre of ground aluminous clay (ordinary clay, but of agootl 

 quality, and soda ash (carbonate of sodium) are heated in a furnace, 

 alnminateof soda and silico-aluminato of soda being formed. The 

 fuse<l mass is then broken into pieces and thrown into an iron tank 

 containing water; the mass is frequently stirred, and finally allowed 

 to .'(ettle. 



The alnminate of soda (being soluble in water) is dissolved, while 

 : !io silico-aluminate of soda (being insoluble in water, sinks to the 

 i.uttom of the tank, with any peroxide of iron that may be present 

 in the clay. 



The liquid is then drawn off, and carbolic acid gas passed tlirough 

 the solution. This decomposes the alnminate of soda, forming 

 carbonate of so<la and pure alumina hydrate. Thus : — ■ 

 2AlXaO. + CO„ + 3 U,0 = XaXO, + 2 Al (OH), 



The alumina hydrate is then dried, mixed with chloride of sodium 

 (common salt) and charcoal or coke, and fom\ed into balls about 

 the size of an orange. These bail.*^ are then taken and put into a 

 vertical earthen retort, and heated to redness ; then a stream of 

 chlorine gas is passed through them. The chlorine combines with 

 the alumina (being greatly helped by the charcoal), and forms 

 chloride of aluminium, which unites with the sodiam chloride 

 (common salt), and distils over or sublimes as double chloride of 

 :iliiminium and sodium thus : — 

 AI.Oj + 2 XaCl + 3C + 3CI. = 3CO + 2 AINaCI^ 



Carbonic Double 



Alumina Common C^-ke. Chlorine Oiido Chloride of 



Salt. Gas. Aluminium 



and Sodium. 

 Ten parts of the double chloride of aluminium and sodium thus 

 formed is mi.^ed with 5 parts of kryolite (a double fluoride of alu- 

 minium and sodium, found in Greenland), which serve as a flux, both 

 in a state of fine powder, and to this mixture is added 2 parts of 

 (metallic) sodium in small pieces. 



The whole is now introduced on to the hearth of a reverberatory 

 furnace, previously heated to the required degree, when a violent 

 reaction ensues. The dampers are then closed, and all parts of the 

 furnace kept as close as possible, to prevent access of air. This 

 causes the mass to completely fuse. When the action has subsided 

 :\nd the decomposition is completed, the furnace is tapped, and the 

 Miotal and slag are run into suitable moulds. Most of the aluminium 

 c lUects in the bottom [of the mould. Above this are two layers 

 (-if slag, the top layer being sodium chloride (common salt), the 

 middle layer being less fusible than the top, and consisting chiefly 

 of fluoride of aluminium, in which small globules of aluminium are 

 niochanically held, which are recovered by pulverisation and sifting 

 of the slag. 



The following equation will show the reaction that takes place in 

 the above reduction. Thus : — 



2A1 + IXaCl + 4XaF 



AlXaCl, + AlXaF, + 6 Xa = 2 Al + 1 XaCl 



Double ' ' ' 



Chloride (A Errolite. Sodiam, AJuminiuni. Common Fluoride of 



Aluminium or CrvoUte. Salt. Aluminium, 



and Sodium. 



There are other methods, but this gives the purest metal, and is 

 "ne generally used in England and France. Messrs. J. Lowthian 

 !'' 11 A- Co. (or Messrs. Bell Bros.), at Washington, near Xewcastle- 

 "H.Tyne, manufactured aluminium on a large scale for several years, 

 iiut gave it up a few years since, owing to it not paying so well as 

 WHS first anticipated, and also on account of the limited demand for 

 the metal. 1 think they used the above method. 



Gateshead. G. W. Gbat. 



DESCEXT AXD DARWIXISM.— TEGETARIAXISM. 



[223] — I wish to protest against the large amount of space M. 

 Donbavand has taken up in stating his ideas. He says that ho 

 sometimes ventures on the labour of thinking. May I venture to 

 suggest that before he again trespasses on your space, he should 

 think over what he means to say, and the shortest and clearest 

 method of saying it ? 



E. M. (letter 170) argues that because uncooked diseased meat 

 is apt to produce tapeworm and trichinosis, therefore we should 

 abstain from animal food altogether. Does he not see that his 

 o«-n argument might be turned with equal force against himself ': 

 Because uncooked unripe fiuit, if eaten at all, and all uncooked 

 fruit, if eaten in quantity, is likely to produce diarrhcea, and so 

 forth, therefore abstain from vegetable food altogether. — Exo.x. 



(©llCllfSf. 



[185] — Cold Satvratei) Soli-tioxs. — Can you inform us as to tlio 

 best method of making and of ascertaining the quantity of salt 

 present in a saturated solution at C0° F ? We have tried a number 

 of experiments, none of which are satisfactory. — F. (iAt'BKBT and 

 C. A. Sevlk.r. 



[180]— The Calculus.— Is a knowledge of the differential and 

 integral calculus gained from, say, Boucharlat's or Hall's treatises 

 suflicieut to begin studying the Mecanique Celeste? — Teia. — [It 

 would bo far from sufticient. A complete course of study of the 

 higher mathematics must intervene, unless you are a born analyst. 

 —Ed.] 



[187]— Flame. — \VTiat are the modifications of the ordinary 

 theory of a gas or candle flame introduced by (1 think) Frankland ? 

 Perhaps you could sometimes give us an article or two on flame, 

 explaining why one kind of burner is better than another. I take it 

 that for a given expenditure of gas, heat + light is constant. Is 

 there a theoretical maximum to light, and what principles require 

 attention in our attempts to attain it ? — L. 



[188] — Intka-Mercuuial Pl.\net. — Leverricr formed a theory of 

 an intra-mercurial planet, for which he surmised some three or four 

 orbital periods. Oblige by informing me exactly what tliese i>eriods 

 were. I do not refer to Lcscarbault's Vulcan, but to the prior 

 hvpotheses and periods of theory.— John Jones. [The only periods 

 that Leverrier dealt with, to the best of my bolief, wore calcu- 

 lated after Lcscarbault's Yvilcan was announced, though Leverricr 

 attempted to reconcile prior supposed observations of planets in 

 transit across the sun's face. — Ed.] 



[189]— Eve-piece.— Can you please give me an easy way to find 

 the power of an eye-piece of 2 plano-convex lenses, both \ inch focus, 

 and sliding one into the other, at a distance from one another, say 

 i inch and i inch ? I want this information, so I may know the 

 power of my telescope. — J. W. C. [The lenses should be set i inch 

 apart. The power is then four times that of either lens alone. — Eu.] 



[190] — The Preservation of Sertulaeias, Zoophytes, Sea- 

 weeds, &c.— Can the Editor of Knowledge, or a correspondent, in- 

 form ma of a chemical preparation to preserve zoophytes, sertn- 

 larias, and seaweeds, &c. ? and is there a book on the subject, and 

 on British and foreign seaweeds, &c. ? — M. A. S. 



[191]— Animal Language.- Do not the habits of swallows, 

 prairie-dogs, kc, seem to prove that animals have some sort of 

 language by which they can make themselves understood — at least 

 to members of their owm family ? — Arachnida. 



'192]— The Ice-age in Britain.- Wliat proofs are there at the 

 present time that there ever existed an ice-age in Britain ?^ 

 Arachnida. 



[193] — Action of Thunder-storms. — Why are beer and milk so 

 frequently turned sour during a thunder-storm, although they will 

 often stand as high a temperature without being affected when 

 there is no thunder in the air? — F. A. S. 



[194]— Gravity.— The editorial rejily to query 14-t is incompre- 

 hensible, if correct. If any force, however small, will overcome 

 the inertia of any mass, however great, what then becomes of 

 the law, that inertia is proportional to mass ? I wish to know 

 what force is necessary to overcome the inertia of one ton weightin 

 a direction at right angles to the force of gravity ?—Zabes.— [Wo 

 repeat, any force, however small. If a ton of matter were sus- 

 pended as vou described, or placed on a perfectly smooth table, the 

 breath of 'a child would overcome its inertia. The velocity 

 communicated to it would be very small, but yon did not say how 

 much velocitv you wanted. — Ed.] 



jRfpIifsf to <Bmxit^, 



[64]— Star Xumbebs and LErtERs.— " A Fellow of the Royal 

 Astronomical Society " says (p. lC-1, Xo. 8) : " Stars ..... are 

 both lettered and numbered in their order of Right Ascension.^_ 

 There should be a comma in this reply, after the word " lettered. 

 The stars ai'e numbered in the order of their right ascension, and 

 Bayer lettered them roughly in order of their brightness. This 

 answers a query by " Winter." — Ed. 



[71] — Xames' ok Flowers. -I would adi-ise Querist 71, m sixth 

 Knowledge, to get Bentham's " British Flora." He will find it 

 everything he desires. Should he fail to get at the right name of 

 a flower by means of this excellent work, I should then recommend 

 him to send a perfect specimen of the " stranger" to the editor of 



