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6. On Niobium.-H. Rose has published in part, the results of his long continued and elaborate investigations of niobium and its compounds-investigations which may justly be considered as among the most difficult and tedious which chemists have ever undertaken. We shall content ourselves with a brief abstract of the most important points in the history of the metal.
Metallic niobium is most easily prepared by heating the double fluorids or hypofluorids of niobiuin and the alkaline metals with sodium to a strong red heat in a crucible of cast iron. After cooling, the black mass is to be diffused in cold water in a platinum capsule; the metallic uiobium boiled with water, and finally washed with water containing a little alcohol, till the washings leave no residue on evaporation. The metal obtained is purer; when a tolerably thick layer of chlorid of potassium is placed upon the mixture of fluorids with sodium before ignition. Metallic niobium is a black powder which conducts electricity, and is acted on by reagents more easily than tantalum. Freshly prepared and still moist niobium when heated with dilute chlorhydric acid is dissolved with evolution of hydrogen. The colorless solution gave with ammonia a voluminous precipitate of a brownish color, which however oxydized upon the filter and became white. It is therefore clear that there exists a stage of oxydation of niobium which is lower than hyponiobic acid. Nitric acid does not dissolve niobium even on heating. Concentrated sulphuric acid dissolves metallic niobium by long heating, the solution has a brownish color and gives a brownish precipitate with ammonia. Fluohydric acid also dissolves niobium, and the solution is effected still more easily by a inixture of sulphuric and fluohydric acids. Fusion with carbonate of potash and boiling with caustic potash, also dissolve the metal. When heated in chlorine the metal ignites, both the yellow and the white chlorid being formed the latter, N22C/3, in large excess. This latter cannot be converted into the yellow chlorid NOC12 by heating in chlorine. The oxydation of niobium yields only hyponiobic acid Nb2O3, and not niobic acid NbO2, so that in this respect the metal differs from tantalum. The density of the metal obtained from the fluorids was 6.297; of that obtained from the yellow chlorid by means of sodium, 6:272, but the density varied greatly in different specimens in consequence of the presence of more or less hyponiobic acid as impurity. When phosphorus vapor is passed over bi-hyponjobate of soda, heated to redness in a current of hydrogen, the metal is reduced and contains only a trace of phosphorus: this reduction takes place much less easily and completely in the case of tantalum. In his second memoir Rose treats of the chlorids of niobium. The yellow chlorid, NbCl2, resembles the corresponding chlorid of tantalum, TaCl2, but has a clearer and somewhat deeper color; it is also more volatile than the latter, beginning to pass over at 125° C., while chlorid of tantalum becomes gaseous at about 144° C. The chlorid of niobium melts at 212° C., and solidifies sooner than the chlorid of tantalum, which fuses at a rather higher temperature. Rose made repeated analyses of the chlorid of niobiun, decomposing it with water, and determining the chlorine and niobic acid produced. These analyses from the extreme difficulty of the subject did not yield results which correspond as accurately as could be desired. The author rejects the results of the first five, and
from the mean of the last three deduces the numbers 48.82 (or 610:37 0 -- 100) as the equivalent of niobium.
Chlorid of niobium, NbCl2, dissolves in chlorhydric acid; after some time the solution becomes turbid and gelatinizes. Water does not completely dissolve the mass, the filtrate is opalescent, and contains much niobic acid, which may however be almost completely separated by boiling. When, however, the chlorid is boiled with chlorhydric acid, a turbid solution is produced, which does not gelatinize, and forms with water a clear solution which is not precipitated by boiling. The chlorid dissolves in alcohol to form a clear solution, while a small quantity remains which gelatinizes with water. When the alcoholic solution is distilled, alcohol, chlorid of ethyl, and finally, chlorhydric acid pass over, while a syrupy liquid remains which dissolves in water, giving a clear solution from which nothing is precipitated by boiling. The syrupy liquid is doubtless niobate of ethyl. When chlorid of niobium is dissolved in chlorhydric acid, water added, and then metallic zinc placed in the solution, a beautiful blue color is produced. Bromine forms two compounds with niobium, one of which is yellowish and voluminous, and corresponds to the hypochlorid, while the other is purple-red, but becomes yellow on strong heating and volatilizes. The yellow color of the hypobromid and the red of the bromid appear to be due simply to the presence of free bromine.
In a third memoir the author treats of the fuorids of niobium. The hydrate of niobic acid dissolves readily in fluohydric acid, and the solution gives a series of crystallized double fluorids. The potassium salts are colorless and crystalline. Of these, one has the formula KF+ NbF2, while the other is (KF + NbF2) + (KF+HF). The soda salts are NaF +NbF2, (2NaF + NbF2) + (NaF+HF), and (NaF + NbF2) + (NaF + HF). It is difficult however to obtain these salts in a state of purity.—Pogg. Ann., civ, 310, 432, 581.
7. On the constitution of titaniferous iron ores.-RAMMELSBERG has published an elaborate investigation of the titaniferous iron ores, the principal results of which are as follows:
(1.) The greater number of the titaniferous iron ores, among them all the crystallized forms, consist of 1 eq. of titanic acid and 1 eq. of protoxyd of iron (prot. of manganese or magnesia).
(2.) Magnesia is an essential constituent of all these ores. In the crystallized mineral from Layton, the magnesia amounts to 14 per cent.
(3.) According to Mosander's theory the titauiferous iron ores are either siinply titanates of protoxyd of iron FeTi; with isomorphous admixtures of titanate of magnesia or mixtures of such with sesquioxyd of iron, for the most part in simple proportions.
(4.) The theory of H. Rose that these ores consist of isomorphous sesquioxyds of titanium and iron, would require the assumption of a sesquioxyd of magnesium.
(5.) The author prefers Mosander's theory for the present state of our knowledge.
(6.) In Iserin we find grains consisting of Feri, and Fef'i 3.
(7.) No titaniferous iron crystallizing in regular octahedrons is known. The dense masses or octahedral grains which contain titanium appear to be mixtures.
(8.) The crystallized magnetic iron ores contain no titanium, they consist of one atom of protoxyd and one atom of sesquioxyd.
(9.) All the Elba iron ore does not contain titanium, but all, like that from Vesuvius, contains magnesia and protoxyd of iron.
(10.) The strongly magnetic octahedrons from Vesuvius, hitherto considered as a specular iron, which are accompanied by rhombohedrons of specular iron, contain in part large quantities of magnesia, and in part protoxyd of iron. They consist either of magnetic iron which has been partially converted into sesquioxyd of iron, as well as of the isomorphous combination Mofe, or, as is more probable, the two protoxyds are isomorphous with sesquioxyd of iron, which is itself dimorphous.—Pogg. Ann., civ, 497.
8. On a new acid obtained by the oxydation of malic acid.-By the action of bichromate of potash upon a dilute solution of malic acid, Dessaignes has obtained an acid which has the formula C6H40s, and which may possibly be identical with the nicotic acid of Barral. The author terins it provisionally malonic acid, and remarks that it is probably homologous with oxalic acid, being the term bitherto wanting between oxalic and succinic acids. Malonic acid forms large rhombohedral crystals, and is easily soluble in water and alcohol. It has a strongly acid taste, melts at 140°, and is decomposed at 150°. By dry distillation it yields a mixture of acetic acid with unchanged malonic acid; carbonic acid is set free at the same time, the equation being
C6H408 = C4H404 + C204. Malonic acid forms neutral and acid salts with the alkalies. Malonate of ammonia precipitates the salts of lime, baryta, silver and mercury. The author remarks that while the analogy between malonic and oxalic acids is strongly marked, the resemblance between malonic and succinic acids is much less distinct.— Comptes Rendus, xlvii, 76.
W. G." 9. Remarks on Chemical Science ; by Sir John HERSCHEL, at the recent meeting of the British Association at Leeds.—Since organic chemistry has assumed, by the experiments and reasonings of Dumas, Liebig, Hoffmann, and its other distinguished cultivators, that highly abstract and intellectual form under which it now presents itself, and which by the links of the platinum bases, and compounds such as those described by Gibbs and Genth, under the name of the ammonio-cobaltic bases, and by those which are every day coming into view by the mutual interweaving if I may use such an expression, of the organic and inorganic systems of composition in bases such as those of the metallic ethyls and those of boron and silicon, it seems to place these conceptions in much the same sort of relation to the ordinary atomic theory as put forth by Dalton and Higgins, and the elementary notions of oxyd, acid, and base of Lavoisier, that the transcendental analysis holds to common algebra. And here perhaps I may be tolerated if I put in a word of reclamation against the system of notation into which chemists who for the most part are not algebraists, have fallen, in expressing their atomic formulas. These formulas have been gradually taking on a character more and more repulsive to the algebraical eye. There is a principle which I think ought to be borne in mind in framing the conventional notations, as well as nomenclatures of every science, at every new step in its progress, viz: that as sciences do
not stand alone, but exist in mutual relation to each other—as it is for their common interest that there should exist among them a system of free communication on their frontier points—the language they use and the signs they employ should be framed in such a way as at least not to contradict each other. As the atomic formulas used by the chemist are not merely symbolic of the mode in which atoms are grouped, but are intended also to express numerical relations, indicative of the aggregate weights of the several atoms in each group and the several groups in each compound, it is distressing to the algebraist to find that he cannot interpret a chemical formula (I mean in its numerical application) according to the received rules of arithmetical computation. In a paper which I published a long time ago on the hyposulphites, I was particularly careful to use a mode of notation which, while perfectly clear in its chemical sense, and fully expressing the relation of the groupings I allude to, accommodated itself at the same time perfectly well to numerical computation, no symbol being in any case juxtaposed, or in any way intercombined with one another, so as to violate the strict algebraic meaning of the formula. This system seemed for a while likely to be generally adopted, but it has been more and more departed from, and I think with a manifest corresponding departure from intelligibility.
The time is perhaps not so very distant when from a knowledge of the family to which a chemical element belongs, and its order in that family, we may be able to predict with confidence the system of groups into which it is capable of entering, and the part it will play in the combination. A great step in this direction seems to me to have been lately made by Prof. Cooke of Harvard University, in the United States, (in a memoir which forms part of the 5th volume of the Memoirs of the American Academy of Arts and Sciences,) to extend and carry out the classification of chemical elements into families of the kind I allude to, in a system of grouping, in which the first idea, or rather the first germ of the idea, may be traced to a remark made by M. Dumas, in one of his reports to this Association, and which is founded on the principle of arranging them in a series, in each of which the atomic weight of the elements it comprises are found among the terms of the arithmetical progression, the common difference of which in the several series are 3, 4, 5, 6, 8, and 9 times the atomic weight of hydrogen respectively. So arranged they form six groups, which are fairly entitled to be considered natural families, each group having common properties in the highest degree characteristic; and what is more remarkable, the initial member in each group possessing in erery case the characteristic property of the group in its most eminent degree, while the others exhibit that property in a less and less degree, according to their rank in the progression, or according to the increased numerical value of the atomic equivalent. Generally speaking, I am a little slow to give full credence to numerical generalizations of this sort, because we are apt to find their authors either taking some liberties with the numbers themselves, or demanding a wider margin of error in the application of their principles than the precision of the experimental data renders it possible to accord, so that the result is more or less wanting in that close appliance to nature which makes all the difference between a loose analogy and a physical law; but in this instance it certainly does SECOND SERIES, VOL. XXVII, No. 79.–JAN., 1859.
appear that the groups so arising not only do correspond remarkably well in their theoretical numbers with those which the best authorities assign to their elements, but that it really would be difficult to distinguish the elements themselves into more distinctly characteristic classes, by a consideration of their qualities alone, without reference to their atomic numbers. When we find, for instance, that the principle affords us such family groups as oxygen, fluorine, chlorine, bromine, and iodine, self-arranged in that very order; or again, nitrogen, phosphorus, arsenic, antimony, and bismuth ; when we find that it packs together in one group all the more active and soluble electro-positive elements, hydrogen, lithium, sodium, and potassium, and in another the more inert and less soluble onescalcium, strontium, barium, and lead—and that without outraging any other system of relations, it certainly does seem that we have here something much like a valid generalization : and I shall be very glad to learn in the course of any discussions which may arise on such matters as may be brought before us in the regular conduct of our business from those more competent to judge than myself, whether I have been forming an overweening estimate of the value and importance of such generalizations.
I will only add on this point, in reference to what fell from our excellent President in his address to the assembled Association last night, that this kind of speculation followed out would seem to me likely to terminate in a point very far from that which would regard all the members of each of these family groups as allotropes of one fundamental one, inasmuch as the common difference of the several progressions which their atomic weights go to make up, are neither equal to nor in all cases commensurate with the first terms of these progressions. For instance, in the chlorine group, the first term being 8, the common difference is 9. Something very different from allotropism is surely suggested by such a relation. It would rather seem to point to a dilution of energy of one primary element by the superaddition of dose after dose of some other modifying element, and this the more strikingly since we find oxygen standing at the head of very distinct groups having very striking correspondence in some respects, and very striking differences in others. But all these speculations take for granted a principle, with which I must confess I think chemists have allowed themselves to be far too easily satisfied, viz: that all the atomic numbers are multiples of that of hydrogen. Not until these numbers are determined with a precision approaching that of the elements of the planetary orbits, a precision which can leave no possible question of a tenth or a hundredth of a per cent, and in the presence of which such errors as are at present regarded as tolerable in the atomic numbers of even the best determined elements shall be considered utterly inadmissible, I think can this question be settled--and when such gigantic consequences-So entire a system of nature is to be based on a principle--nothing short of such evidence ought, I think, to be held conclusive, however seductive the theory may appear. I do not think such precision unattainable, and I think I perceive a way in which it might be attained, but one that would involve an expenditure of time, labor, and money, such as no private individual could bestow upon it. If the phenomena of chemistry are ever destined to be reduced under the