"- 







[ALUMIMI \i. 



earth*. Although the face of nature praonte a incut 

 dirertified appearance, from the barren roolu to tho 



. M.-.1 mil, utill the number of earths in \--ry In 

 ami taking the average i'f A-C., of this kingdom, 



we do not find iu enneotisl ingrodiouU to exceed three 

 or four in number, of which ilcx, lime, and alumina are 

 the chief. Of course, in minute .|nanlities, many 

 ubcUaoes) are present, which art eaientul to the growth 

 and existence of plant*. Common clay is a mixture of 

 alumina and oxide of iron. The sand of our hills and 

 the tea-chore is oompowd of silicious matter, or i-mnd. d 

 flint Grarel U mostly compoied of lilex and oxide of 

 iron, which give* it it* colour. The chalk rockx, which 

 abound in Kent and other places, are nearly pure .- ,. 

 bonate of lime. Granite, felspar, quarte, <tc,, which 

 form the primitive rock*, are chiefly composed of silex ; 

 whilst th.wc of the tecondary and other formations 

 hare alumina, silex, magnesia, and lime, in constantly 

 varying proportion*. The earths have been divided into 

 rUisoi ; namely, earths proper, and alkaline earths ; of 

 the latter, are lime, magnesia, baryta, and strontia. To 

 the general observer of nature, as well as to the geologist 

 and chemist, the disintegration of the rocks, and the 

 pr.-d Hi-lions of soil, are matters of deep interest. The 

 action of air and water gradually crumbling down the 

 most solid mass ; the first evidence of vegetable existence, 

 as seen in the humble moss, which, whilst rubbing tho 

 rock to supply itself with food, converts that rock from 

 a barren waste to a fruitful soil ; the liberation of the 

 constituents of the rock, which afterwards afford nouri -h- 

 ment to the grass and tree ; these and numerous other 

 changes, gradually but constantly taking place, invest 

 tho study of the earths with tho deepest interest But 

 we must reserve our remarks on this subject for that of 

 Agricultural Chemistry, in which we may more properly 

 dilate on the variety of changes which occur in the 

 production of soil, plants, ic. ; and we shall at once pro- 

 ceed to describe the earths, the metals, and compounds, 

 together with their varied uses in commerce, medicine, 

 and manufactures. 



ALUMINIUM. 



ONK of the greatest curiosities of modern times, is the 

 production ofa valuable metal from common clay, which, 

 in its pure form, is simply an oxi<le of thu metal alumi- 

 nium, or, as it U also called, aluminum. Its discovery 

 has resulted from those of Sir Humphry Davy, who, as 

 we have already remarked, was the tint to prove that 

 the alkalies, potass, and soda are the oxides of metals. 

 Aluminium has a specific gravity of 2'5 ; aud is there- 

 fore of about the same as that of glass ; its symbol is 

 Al ; and the equivalent^* 1117. 



It is best produced by the process of M. St. Claire 

 Deville, of Paris, to whom we are indebted for the com- 

 mercial importance of the metal. A mineral called 

 " cryolite" is it* most convenient source ; but the follow- 

 ing plan may be adopted to procure it from clay : This 

 material, with sugar and charcoal, is to be made into a 

 paste, which is then to be placed in a platina tube. 

 The tube is to be heated in a convenient furnace to a 

 red heat ; and chlorine gas U passed over tho paste. 

 By these means the chlondo of aluminium is produced 

 through the following chemical change which takes place. 

 The oxygen leave* the aluminium of the clay, and the 

 lilorinc takes its place ; so that we find the chloride 

 formed in place of the oxide. Now, as tho chloride of 



metal is very easily sublimated or removed by 

 it poodily pssses away from tho platina tube, and col- 

 lect* in a receiver placed at the other end of the tube, 

 in the form of a primrose-coloured powder.* Groat care 

 must bo taken that the atmosphuro has no access to the 

 receiver, because tho moisture it naturally con 



id be absorbed by the salt-like substance, and such 



i Id be thereby rendered unlit f<, r the purposo of oh. 



taining the metal Tho chloride thus produced is tip n 



_ heated with the metal sodium, by HUMUS of which the 



chlorine U taken fp-m the .iliiminiiiin, and combines 



with the sodium, forming common salt Tho > 



aluminium is thou found at the bottom of the cm 

 of a white colour, and lnvin,- the appearance o 

 and in m is similar to th 



The first bar of aluminium which was exhibit.- 1 in 

 this country, was sent by the present Emperor of tho 



li to the Polytechnic Institution, Regent-si: 

 London ; and it excited, at the time, the deepest interest 

 in scientific circles. On the occasion of its first exhibition, 

 many of tho leading scientific celebrities of tin- kingdom 

 were present ; and Messrs. Hunt and |;-..1>.-!1. of I: 'Mi- 

 street (her majesty's jewellers), kindly lont numerous 

 specimens of emeralds, and other precious stones, for tho 

 purpose of elucidating the rationale of the process. Wo 

 m iy hero remark, that emeralds, rubies, garnets, and the 

 corundum, with other gems, are largely composed of 

 aluminium in the state of oxide such as the pure 

 alumina, of which we have been speaking. 



Aluminium is susceptible of a high polish. It has 

 naturally a whiter colour than pure silver ; aud whilst 

 that metal soon tarnishes, or loses its polish when ex- 

 posed to air containing sulphur, which invariably occurs 

 in places wherein coal-gas is burned, aluminium retains 

 its polish, because its affinity for sulphur is very alight. 

 It is very ductile, and may therefore be drawn into a 

 wire. It may also be easily beaten out into sheets or 

 plates, and in that form may be employed for a vast 

 variety of purposes. It has been made into brooches, 

 spectacle-frames, helmets, spoons, chemical apparatus, 

 and various other utensils ; and, so far as we can judge, 

 it promises to be of extreme value, generally speaking, 

 in its employment for all purposes where freedom from 

 action by chemical agents is required. 



Tho sulphuric, nitric, and hydrochloric acids have but 

 a slight, if any action on it. Indeed, in our own ex - 

 periments we have found that its chief enemy (if we may 

 so call it) is any kind of alkali, such as potass anil 

 soda. 



If a bar of tho metal be immersed in either of these 

 alkalies, the water in which they are dissolved is at once 

 decomposed, aud hydrogen gas is given off. A jelly-liko 

 substance forms on the surface of the me'--l ; aud on 

 chemical examination, such is found to 1 : hydrate 

 of alumina. This, however, only occurs when the alkaline 

 solution is very strong a circumstance rarely, if ever, 

 occurring in daily life. 



It will thus be observed, that modern chemistry, al- 

 though it does not turn whatever it touches lift rally into 

 gold, yet it has the power of producing from the 

 du-t which we shake off our feet, a metal valuable to 

 us iu the highest degree. It may be safely .s.u.l of 

 experimental science 



" Whatever it touches It adorn*.." 



Give the chemist the refuse of our manufactures, and 

 lie will, by tho potent aid of his art, almost create that 

 which is truly valuable from that which appeared next 

 akin to nothing. He calls out of tho chaos of nature its 

 most valued elements ; and by tho intelligence which ho 

 exercises, he invests with interest that which had been 

 a mat tor of offence and repugnance. 



Alumina is tho only oxide of tho metal ; and it ; 

 be produced by adding a solution of carbonate of ain- 

 iii'. nia to one of common alum. The precipitate, when 

 diied, affords a white powder, which is tho earth alumina. 



This substance, as found in t he form of clay, is of - 

 importance; and as such, is thu material from which 

 China, pottery, bricks, AT., are produced. The colour 

 of clay varies considerably ; the purest, or " kaolin," 

 being nearly white. London day has a slate or 

 blue colour; whilst thai from which the lower kinu 



pans, bricks, an 1 n]r< are produced, is of a brown 

 tint before hein,' Invited, and aM.uns a red colour ;i 

 'in,' the process of baking. 



The quality of white It, e .. Mp:n-ati\v ncy, 



etc., found in tho highest kinds of porcelain, a 

 the natum of the clay employed in the urn. 

 With th" kaolin, a quantity of flint, n-ln.--.l io an im- 

 palpable powder, is mixed, so that an bo . 

 paste is produced. This then uinliM-gous the | 



