obtained by disoxidation- contained 0.87 [13.44 grs.] of earth; consequently there were 3.69-0·872·82 gr. [43.56 grs.] of pure iron. In the analysis of this iron 4.07 gr. [62.86 grs.] of red oxide were obtained: the red oxide therefore contained 4.07-2·82=1.25 gr. [19.31 grs.] of oxigen; and consequently was at 100 per cent, or 44 per cent and upward, (allowing for any trifling errour). Elba. As to the iron of Elba, we find by calculation, that the and that of red oxide obtained was at 43 per cent and upward, allowing likewise for any trifling errour; and if we take the mean of the two results, admitting decimals and allowing for any little errour, we shall find, that the red oxide is at 44 per cent. In some troublesome experiments, which I shall not de- Hidrogen obscribe, I was employed to obtain hidrogen by the decom-tained by passing water over position of water. For this purpose I took some very fine iron wire. iron wire, which I weighed and introduced into a gunbarrel, adapted to this a retort filled with water, and proceeded in the usual way. After the process I had a wire extremely State of the increased in size, consisting of an assemblage of octaedral iron. crystals so small as to be visible only by a lens, and forming a fragile wire oxided in all parts. I weighed it, and as there were still some parts that had been less heated, and not perfectly oxided, I pulverised the oxidule, subtracted the iron thus separated, and on calculation found I had an oxidule of 32 per cent and upward. DESROCHES. This is to certify, that these experiments were made at the laboratory of the School of Mines in the month of August, 1809. LE BOULLENGER. Observations by Mr. HASSENFRATZ. Mr. Hassen It follows from the experiments of Mr. Desroches, that Observations by the oxidule of Cogne lost 0·317 of oxigen, which amounts fratz. to 46 parts to 100 of iron; and that the oligist iron of Elba lost 0.3537, which would make more than 54 to 100 of iron The More loss in The oxidule of Cogne, treated with charcoal, in one experiment yielded from 5 gr. [77.23 grs.) a button con. taining 3.42 gr. [52·82 grs.] of iron, and 0.66 of a gr. [10.19 grs.] of scoria, which would make the loss about 27 to 100 of iron; and in another experiment the 5 gr. yielded a button containing 3.38 gr. [52.21 grs.] of iron, and 0.78 [12.05 grs.] of scoriæ, making the loss 25 to 100 of iron. We will take the highest term, 27. The oligist iron of Elba yielded from 5 gram. a button of iron weighing 3.6 [55-6 grs.] and 0.1 [1.54 gr.] of scoriæ; which would make the loss 30 to 100 of iron. Thus the difference of loss in the two modes of reducing the reduction the oxide of iron would be for the oxidule of iron of by hidrogen than in that by Cogne 46 by hidrogen, and 27 by charcoal; and for the oligist iron of Elba 54 by hidrogen and 30 by charcoal. charcoal, Possible causes of the difference. Addition to the With regard to the causes, that may produce this dif ference, we may distinguish three: 1, the charcoal, that combines with the iron, when the metal is fused with this combustible: 2, the oxigen, that may remain combined with the iron in the metallic button obtained: 3, the action of the hidrogen on the iron, the gas dissolving and carry. ing off some of the metal. Desirous of knowing what might be the influence of each iron by carbon, of these causes, I fused in a crucible lined with charcoal 5 gr. of iron wire previously soaked in oil, and obtained a button weighing 5.13. Hence it follows, that somewhat less than 0.03 of carbon was combined with it. and by carbon and oxigen. Difference between the two ores. I afterward dissolved 5 gr. of iron in nitric acid, in order to oxidate the metal to a maximum; moistened the oxide with oil; placed it in a crucible lined with charcoal to fuse it; and obtained a button weighing 5.2: consequently 0-04 of carbon and oxigen had combined with the iron. Supposing, that 0·04 of carbon and oxigen remained in the buttons obtained from the oxidule of Cogne and the oligist iron of Elba, it would follow, that the oxidule of Cogne had lost near 32 per cent of oxigen, and the iron of Elba near 36. These two results agree in placing the oxidule of Cogne in the rank of black oxides obtained by the decomposition of water over iron; for this proportion of 32 is nearly what what I have deduced from the experiments of several able chemists on the composition and decomposition of oxidules of iron. It is also the same as Mr. Desroches has deduced from the experiments he made this year at Moutiers. It follows too from these experiments, that the oligist iron is more oxided than the oxidule, as the learned Mr. Hauy had concluded from the colour of these two ores when powdered. But when we have taken account of the carbon and Loss in the reduction by hioxigen combined in the metallic button obtained from the drogen not thus disoxidation of oxides of iron by charcoal, it appears, that accounted for. the loss they undergo in their reduction is still less than that which occurs when they are disoxided by hidrogen; since in the latter case the oxidule of Cogne lost 46 to 100 of iron, while it lost but 32 in the reduction by charcoal; and the iron of Elba lost 54 with hidrogen, and only 36 with charcoal. Is this difference ascribable to the solvent action of hi. Iron apparently dissolved and drogen? Some observations seem to warrant this conclusion. carried off by 1, When the hidrogen gas obtained by the decomposition of the hidrogen. water passed over iron, or by dissolving this metal in acids, or otherwise, is preserved in jars over water, the interior of the jars sometimes becomes coated with a slight stratum of oxide of iron. 2, At the end of the account of his experiments Mr. Desroches had added the following note. "A great deal of ferruginous hidrogen gas was evolved, as I found by its smell; so that probably some iron was lost in the passage of the hidrogen gas through it." I do not think however, as Mr. Desroches observes, that This deserves Inquiry. we should hastily conclude hidrogen to have a solvent action on iron from his experiments alone. They should be repeated and varied in several ways, before we decide on a fact of such importance. It is sufficient for me at present to have called the attention of chemists to a result, that is worthy their consideration. X. Determination X. Determination of the Quantity of Hidrogen and of Ammonia contained in the Amalgam of Ammonia: by Messrs. GAY-LUSSAC AND THENARd*. Quantity of hi-WE took 3.069 gr. [47-403 grs.] of mercury, placed drogen contained in amalgam of ammonia. Quantity of am them in a small cupel of sal ammoniac at the negative pole, A second experiment, made also with six buttons of soft amalgam, having afforded results scarcely differing from the preceding, they may be considered as exact, or at least as approaching very nearly to the truth. It may happen however, that, on a repetition of these experiments, other numbers than ours may be found; and this must necessarily be the case, if the amalgam were not made so as to obtain it soft, or so that the mercury entering into it should have its bulk at least quintupled. We imagined at first, that by amalgamating a given quantity monia contain of mercury and deducting the known weight of the mercury ed in amalgam of ammonia. and the hidrogen it contained, we should find exactly the quan. tity of ammonia entering into the amalgam. But we soon * Annal. de Chim. vol. lxxiii, p. 209. Extracted from a paper read to the Institute, September, 1809. found found, that this mode of analysis was very inaccurate: 1st, because the amalgam is half destroyed before it is well dried : 2dly, because this amalgam displaces a volume of air, of which it is difficult to take account: 3dly, and lastly, becanse, on introducing it into the phial, the hidrogen and ammoniacal gas evolved take the place of a quantity of air, which cannot be estimated, and must necessarily occa sion great errours, in the results. Hence the weights of all differed from one another. One gave us on 3.069 gr. of mercury an augmentation of 0.002; another, an increase of 0.003; a third, of 0·0045; and a fourth, of 0·001 only, It is even possible, that a loss of weight might appear, since the air of the phial is replaced by hidrogen and am. moniacal gas. Such no doubt were the causes of Mr. Davy's mistake, when he found that mercury, in forming an amalgam, was increased only a twelve-thousandth of its weight. Impelled by these reasons to reject this mode of analysis, Mode of anawe employed the following, which we consider as very lysis employed. exact. Knowing the quantity of hidrogen contained in the ammoniacal amalgam; and not doubting, that the hidrogen and ammonia were in a uniform proportion to each other in this amalgam, we had recourse to this proportion, to determine the whole quantity of the ammonia it contained. For this purpose we converted into amalgam 3.069 gr. [47.403 grs.] of mercury; after the amalgam was well dried with blotting paper, we introduced it immediately into a small jar very dry, and a quarter filled with mercury; and immediately too clapping a finger on the mouth of the jar, we shook the whole together for a few minutes. In this way the portion of amalgam that still subsisted was decomposed, the hidrogen and ammonia it contained returning to the state of gas; for the moment the little jar was immersed in mercury and unstopped, the mercury was seen to sink. Three other similar experiments were made, in order to obtain more decisive results; and after each experiment the gasses were passed into one and the same very dry tube filled with mercury. When they were thus all collected in the tube, the quantity of ammonia they contained was determined by agitating them with water. Then, to |
