544 



METALS. 



METEOES AND METEORITES. 



named metal or previously coppered become 

 covered with a white deposit, consisting of 

 an alloy of zinc and cobalt, zinc and nickel, 

 etc. 



New Method of Preparing Aluminium. The 

 method thus far generally employed for the 

 preparation of the new metal, aluminium, has 

 been that originated by M. Deville, at the works 

 of Salyndre, and which in essential features is 

 identical also with that described under the 

 title MAGNESIUM, as in use for the separation 

 of the metal named the magnesian being of 

 course, however, replaced by aluminic chloride 

 in the process. It is quite fully stated in the 

 Annuaire Encyclopedique for 1864, and is in 

 fact now generally well known to metallur- 

 gists. The general steps involved in it are three 

 1, the preparatory reduction of sodium ; 2, 

 fabrication of the double chloride of aluminium 

 and sodium ; 3, reduction of aluminium by re- 

 action of the two materials named, and by aid 

 of heat. Besides the largest item of expense 

 in this method the cost of preparing the 

 sodium another source of increased cost in the 

 product exists in the apparently necessary use 

 of the rare mineral cryolite, and which contains 

 both the metals involved in the process, as a 

 flux in the final reduction. 



M. Basset, however, has lately revived in 

 more successful form the use of zinc, proposed 

 , some years since, for the reduction of alumin- 

 ium. He fuses the chloride of aluminium 

 with excess of zinc ; and he states that the re- 

 sults are a chloride of zinc and an alloy of 

 zinc and aluminium, from which latter all the 

 zinc (volatilizable at such temperature) may be 

 driven off at a white heat. It is stated that by 

 this plan the cost of aluminium is likely to be 

 greatly reduced, so that the metal may be made 

 cheap enough for many ordinary mechanical 

 uses. 



Mr. Corbelli separates aluminium from clay, 

 by first purifying the latter from foreign mat- 

 ters, then drying, treating with six times its 

 weight of sulphuric acid to remove iron, allow- 

 ing the clay to settle and drying again, mixing 

 with about twice its weight of prussiate of pot- 

 ash the quantity of this, however, to be in- 

 creased or diminished according to the amount 

 of silica in the clay, adding to the mixture com- 

 mon salt to the amount of one and a half times 

 the entire weight, and then heating the whole 

 together in a crucible to white heat. After 

 cooling, the reduced aluminium will be found 

 at the bottom of the crucible. The principal 

 manufacturers at the present time of aluminium, 

 in England, are Messrs. John Bell & Co., of 

 Newcastle. 



Supposed Passive State of Metals. M. "W. 

 Ileldt has made numerous experiments in con- 

 nection with the subject of the so-called pas- 

 sive state of metals, or that in which it has for 

 some years past been supposed that certain 

 metals have been rendered insusceptible of being 

 acted ou by ordinary chemical agents. He 

 finds that the change actually taking place is 



one that is confined merely to the surface of 

 the metals in question those, namely, the 

 nitrates of which are insoluble in nitric acid ; 

 and that the passivity belongs to this insoluble 

 layer only, and does not indicate any particular 

 electro-dynamic state or polarization. It is, in 

 fact, only those metals the nitrates of which are 

 soluble in dilute nitric acid and insoluble in 

 the concentrated acid that present the phenom- 

 ena of apparent passivity. With copper and 

 tin the insoluble layer is visible to the naked 

 eye ; with other metals it may be seen by aid 

 of a lens. Acidulated water easily removes it, 

 and the metal returns to its normal condition : 

 the liquid contains nitric acid and also metallic 

 oxide. If iron that has been rendered inactive 

 be subsequently touched with copper, zinc, or 

 even iron itself, and either in the liquid or after 

 being withdrawn from it, the disengagement 

 of gas recommences, and the chemical action is 

 renewed, and that simply because the protect- 

 ing coating has been disturbed. 



Many other curious results are noted in con- 

 nection with the subject, for which the reader 

 must be referred to the abstract of M. Heidi's 

 paper, Chemical News, November 26, 1864, or 

 to the original, in Les Momlcs. 



METEOES AND METEOEITES. Under 

 the first of these terms may be included the 

 familiar and constant phenomenon of the so- 

 called " shooting" or " falling stars," which 

 disappear in the upper atmosphere, and with- 

 out leaving any discoverable traces of their 

 substance, and also those solitary incandescent 

 bodies likewise known as meteors, in the most 

 specific sense, and as fire-balls or bolides 

 which at rarer and irregular intervals make 

 their appearance within our atmosphere, moving 

 in any direction and at various rates of speed, 

 emitting light along their course, in many in- 

 stances bursting into fragments with an audible 

 report, and sometimes in form of such frag- 

 ments, or else entire, reaching the earth's sur- 

 face, perhaps to bury themselves in the soil ; 

 while under the second term are to be included 

 the various solid masses thus coming from the 

 regions of space, either unobserved or as visible 

 meteors, and the peculiar and now known 

 characters of which, in respect to structure 

 and composition, decide that they have not 

 been of terrestrial, but of cosmical origin 

 these bodies being also known as meteoric 

 stones, and as aerolitJis or aerolites. That 

 these are all but so many forms of one and the 

 same phenomenon, is now generally admitted, 

 and grounds for the conclusion will appear 

 in course of this article. Many details of 

 the papers from which we collate are ex- 

 cluded by want of space ; and the scientific 

 reader, in particular, must be referred to the 

 original articles for the data and trains of rea- 

 soning upon which rest many of the results to 

 be stated. Brief notices of some of the ob- 

 servations of the past three years will first be 

 in place. 



November Per iod In the year 1863 observa- 



