nearly insoluble in water. In carbonate of ammonia and caustic ammonia it dissolves, forming a deep green solution: a hot saturated solution, on cooling, parts with a salt in brilliant green prisms, with a tint of golden yellow, which appears to be the chromate of ammonia and copper produced by M. Malaguti by another process. This double salt of potassa is instantly formed, when recently precipitated hydrated oxide of copper is mixed with bichromate of potassa in solution; it may also be obtained by mixing a solution of sulphate of copper with a solution of bichromate of potassa in excess, caustic potassa being gradually added. The precipitate, first of a pale color, afterwards becomes darker and crystalline. NEW PROCESS FOR DETECTING BY ALVARO REYNOSO. This salt, on being burned, yields water and oxygen, and a mixture of oxide of copper, THE means employed for detecting these oxide of chromium and chromate of potassa bodies, when they exist in the form of iodides remains; the latter may be, at least, partially or bromides, consists in dissolving them in dissolved out by means of water. To analyse water, adding starch in the state of paste, this salt it was dried over sulphuric acid, and or ether, and a few drops of an aqueous soludissolved in bydrochloric acid; the copper tion of chlorine. The chlorine seizes the was separated by means of sulphuretted hy-metal combined with the iodine or bromine, drogen, and weighed in the manner usually adopted for calcined oxide of copper. The liquid filtered from the sulphuret of copper was boiled in order to expel the excess of gas, and the oxide of chromium was precipitated with ammonia. When completely separated by long boiling, it was collected in a filter, ignited and weighed, and calculated as chromic acid. The solution filtered from it was evaporated to dryness, and the salt was heated in a platinum crucible, to volatise the hydrochlorate of ammonia. The potassa was then weighed as chloride of potassium. In three analyses, made respectively with 1478, 1.666, and 0.944 grammes of salt, prepared at different times, the following proportions were obtained : and these bodies color the starch blue, or dissolve in the ether: but, as iodine and bromine have the property of combining directly with chlorine, forming chlorides of iodine and bromine, indicating the presence of these bodies, chlorine should not be used in excess, because the chlorides of iodine and bromine are decomposed by contact with water, producing hydrochloric and iodic or bromic acids, which have no action on starch or ether. This experiment was very difficult to perform frequently when it was desired to find these bodies, they were not found. It was believed that this was owing to the above inconvenience. The quantity of chlorine was then diminished, in the fear of exceeding the necessary proportion, and it happened that the quantity of chlorine was not sufficient for liberating the iodine. The man- ́ ner in which chlorine was employed also led to error; indeed, it is known that a solution of chlorine weakens with time, and that it ultimately disappears altogether, despite all possible precaution. Thus, on pouring into the solution of an iodide or bromide a small quantity of chlorine water, it happened that the iodine was not set free, and that all the chlorine was employed in forming hydrochloric acid. This method was not, therefore, applicable to the detection of small quantities of iodides or bromides, especially when mixed with solutions capable of taking the chlorine. Hence it was desirable to iso Chromic acid 43-549 42.665 43.261 *Annales de Chimie et de Physique, D late iodine and bromine by means of a body incapable of acting on them, even in excess. Oxygenised water entirely fulfilled these conditions. It decomposes hydriodic and hydrobromic acids, without having any action on the iodine and bromine liberated. The following is the process for iodine: a piece of binoxide of barium is put into a small tube closed at one end: distilled water, pure hydrochloric acid, and the paste of starch, are added when bubbles appear on the surface and the iodide. A rose-blue color is instantly perceived when the quantity of iodine is rather considerable, and of a deep blue when the quantity is great. It is more convenient to operate in these conditions, for both the ease and success of the experiment. In this manner we are safe in employing an excess of oxygenised water, which is necessary where hyposulphites, sulphites, or sulphurets exist; besides, the hydrochloric acid employed in the preparation of the oxygenised water also performs an important part, for it serves to liberate the hydriodic acid : BaO2+ (Cl H)2+IH, PoO+ HO=BaO, C1l H+ POO, C1 H+ 2 (HO) + I. Although it is beyond doubt that hydrochloric acid, in acting on the deutoxide of barium, in presence of water, produces oxygenised water, I desired to ascertain that it was indeed H 02 that produced the result obtained: I then substituted tartaric acid for the hydrochloric acid, and I attained the same end. M. Thenard, moreover, had noticed the composition of hydriodic acid by pure oxygenised water. When the iodides are mixed with chlorides, sulphurets, sulphites, or hyposulphites, the process is quite as accurate; only, as by the action of the hydrochloric acid on the sulphuret, sulphuretted hydrogen is produced, which is decomposed by the oxygenised water, and on the hyposulphites acid sulphites pass to the state of sulphate absorbing oxygen, a greater quantity of oxygenised water is required than if the iodide were pure. The hyposulphites and sulphites, in passing to the state of sulphates, produce in the liquor a precipitate of sulphate of baryta, which might arrest the action if not stirred so as to detach the sulphate of baryta from the surface of the deutoxide of barium; moreover, this should always be done to increase the production of oxygenised water. By this process, I very readily detected the presence of iodine in the urine of a patient taking 0-10 centig. of iodide of mercury morning and evening. By means of chlorine, the same urine gave no result. This was a case in which, notwithstanding all precautions, the iodine passed unperceived by the chlorine, This process detects the presence of iodides in the ashes of sponge. One drop of a solution of 0.010gr. of iodide of potassium dissolved in a quart of water, produced, every time that it was dropped into the tube, a very striking blue color on the surface. On stirring, the blue color disappeared, and the liquor assumed a rose tint; by adding another drop the blue color on the surface was again obtained. Thus this process very conveniently indicates the presence of 108000 of iodide of potassium. For bromine the process is the same, only ether is used instead of starch. It is stirred, the bromine dissolves in the ether, and gives rise to a yellow color, which is more or less deep according to the quantity. The ether may be done away with, and starch used instead. We have then a reddish yellow precipitate throughout the tube, of bromide of starch. This means is more convenient. Bromine, in acting on starch, produces a true combination, and not a simple penetration, as M. Dupasquier supposes. (Traité de Chimie, tome i., 648.) The proof that it is a combination is, that ether agitated with it does not acquire any color, and, consequently, does not decompose it; also, starch discolors ether holding bromine in solution. If iodine and bromine did not both combine with starch, they might be separated by setting them free in the presence of starch: the iodine would combine with the starch, and the bromine might be dissolved in a little ether added to it, so as to obtain a blue color below and a yellow one above; but as both possess that property, and, as, moreover, bromide of starch is undecomposable by ether, we cannot operate in this manner. We must, therefore, recur to M. Dupasquier's method, and employ it with all possible caution against errors. As bromine requires more chlorine than iodine to make it disappear, it is the less subject to inaccuracy. ON THE EXTRACTION OF VANADIUM FROM ITS ORES AND SLAGS. BY ISAIAH DECK, DUBLIN. THE analysis of many varieties of slags, and furnace products, in searching for the rarer elements, and investigating the curious differences observed in the admixture with the baser metals, as regards malleability, ductility, &c., has led me to adopt a process for the extraction of vanadium, which, differing somewhat from those hitherto used, possesses an advantage in the readiness and certainty THE ATOMIC, WEIGHT OF TIN.* with which it ensures the thorough separation | REMARKS ON BANCA TIN AND ON of the chromium, which I have found in almost every instance associated with it. The substance is to be well powdered, and mixed with a fourth of its weight of nitre, and heated in a reverberatory furnace at a cherry red for some hours. The shrunken coherent mass is digested in boiling water, and filtered. The filtrate is carefully neutralised with pure nitric acid, and precipitated with acetate of lead, adding sulphurous and dilute sulphuric acids until the resulting precipitate is white. Filter and boil with caustic potassa, which precipitates the chromium-filter and boil with hydrosulphate of ammonia, or precipitate in the cold with sulphuretted hydrogen-collect the precipitated sulphuret of vanadium and fuse at a low red heat with twice its weight of nitredissolve in water, filter, and immerse sticks of muriate of ammonia in the solution for three or four days. The crystals of vanadiate of ammonia separate in a granular form, and may be purified by re-crystallisation, or converted into vanadic acid by the appli cation of a low red heat. I have found this rare metal to be much more diffused than is generally supposed but in very minute quantity, and by the above process have lately detected it in a peculiar metallic-looking sand from the shores of Murray Bay, River St. Lawrence, in the form of a silicate of vanadic acid-combined, as usual, with small quantities of chrome and copper, and is probably derived from the detritus of the surrounding metaliferous rocks. BY PROFESSOR MULDER. THE samples of Banca tin operated on by Dr. Mulder were presented by the Society of Commerce to be examined for the Government. It was the desire to obtain from Banca tin ore tin quite pure, with the exception of a little iron. The examination of mines, imported in different ships, showed twenty samples of Banca ore from different them to consist of almost chemically pure tin. sample, and oxidised with nitric acid, and A piece was cut out of the centre of each then diluted with a small quantity of water before being filtered. This loss arising from liquid was neglected as insignificant; it the trifling solubility of the tin in the acid contained, besides, traces of iron, lead, and arsenic. The insoluble oxide of tin was calcopper, but neither silver, antimony, nor lyses are given below. cined and weighed. The results of his anaThe names in the first column are those of the vessels in which the various kinds were brought; the second contains the quantity of tin used for analysis; the third the amount of oxide of tin obtained upon oxidation with nitric acid; and the fourth the amount of pure tin, supposing that the oxide of tin contains in 100 parts 78.616 tin and 21.384 ........ 13 Koniginn du Nederlanden 14 Zeemanshoop .... 15 Anna en Elise.. 16 Josephina en Catharina 17 Flora 18 Christopherus Columbus 19 Adm. Jan. Evertse.... 20 Doctrina et Amicitia * Scheik Onderzoek, Part V., No. 4., p. 250. From the fourth column we obtain the arithmetical mean 1999-96: 20=99.998, by which it appears that all these samples, considering how trifling the difference of the numbers is, are almost chemically pure tin, especially remembering that a little tin was left in the nitric acid solution. The solution from all the samples being mixed, deposited, when evaporated nearly to dryness, 0.210 of oxide of tin; and about 0.0061 grammes of oxide of tin was separated from the other metals in the residue. Now, since there were 201.877 grammes of tin taken for the twenty analyses (see column 2), and the amount of oxide of tin obtained therefrom was 256-7735 grammes (see column 3), we find, on adding to the latter number the oxide of tin subsequently obtained, that 201.877 grammes of tin give 256 9896 grammes of oxide of tin. In the residue, from which had been separated the last quantity of oxide of tin, was found an amount of oxide of iron corresponding to 0 0395 grammes iron, oxide of lead corresponding to 0.0257 lead; oxide of copper to 0.0126 copper. Not a trace of any other metal could be found in the nitric solution, although tested for arsenic and antimony in Marsh's apparatus. According to this, Banca tin contains the following: 201-8770 100.000 From the excesses obtained (see column 4) we are justified in assuming that the atomic weight of tin requires some modification. With respect to the facts ascertained by experiment, there was obtained from 201.8770 grammes Banca tin, containing 201-7992 grammes pure tin, 256.9896 oxide of tin after the removal of the foreign metals, consequently 201-7992 grammes of pure tin have 201.7992 absorbed 256.9896 55.1904 oxygen. If we calculate from this the composition of the oxide of tin for 100 parts, we find for 78.524 of tin 21.476 oxygen, which makes the atomic weight of tin 731.230, whereas Berzelius made it 735.296. The above results had another object than acertaining the composition of the Banca tin, and are, in consequence, not suited, especially from the numerous weighings, to establish the atomic weight of tin; but, as they indicated that the equivalent of tin was too high, some experiments were made with chemically pure tin, for this especial purpose, by Mulder and Vlaanderen, 100 parts of tin being given. Vlaanderen, moreover, analysed three other kinds of Banca tin, which contained about the same amount of foreign metals as the above-mentioned. Three oxidations of the first gave, for 100 parts of Banca tin respectively, 127.750, 127-707, 127-701 oxide of tin; 100 parts of the second kind furnished 127.50; and 100 parts of the third kind, 127.69 oxide of tin. These numbers differ but little, and from the coincidence of the analysis by Mulder and Vlaanderen, marked a, these would appear to be most trustworthy, and the atomic weight of tin would be 725.7. As, however, analysis cannot guarantee the value of 0.7, Mulder proposes, in order to obtain a whole number, to adopt 725, that is, 58 × 12.5 as the atomic weight of tin. The analysis b of Vlaanderen gave the number 729.2; nearly the same atomic weight as was deduced from the above twenty experiments (731.230). Admitting the equivalent 725, the composition of 100 parts of the oxide of tin would be 73.38 21.62 ON BEE'S WAX.* BY DR. VOGEL, JUN. THE production of cerine and myricine from wax by means of boiling alcohol, having always given unsatisfactory results, Dr. Vogel, jun., employed chloroform, and found that from six to eight parts of this liquid poured on white wax, and left standing for some time at the ordinary temperature, always dissolved a quarter of the wax, leaving the On remaining three quarters as residue. evaporating the chloroform, a soft, clammy substance remains behind, which readily dissolves in chloroform. The undissolved wax is granular and very friable. It is, however, still undecided whether the two substances obtained in this way from wax, are or are not identical with cerine and myricine. Be this as it may, chloroform presents a convenient test for detecting the adulteration of white wax by tallow or stearic acid, since these substances are not readily dissolved by it at a low temperature. Consequently, if white wax, heated with from 6 to 8 times its own weight of chloroform, loses more than one-fourth, we may conclude that it is adulterated. *Buchner's Repertorium. ON THE PRODUCTS OF THE DISTILLATION OF LACTIC ACID AND LACTATE OF COPPER.* BY DR. ENGELHARDT. FROM highly concentrated lactic acid, at a temperature of between 266° F. and 284° F., a watery, acid, and rather empyreumatic liquid-dilute lactic acid-slowly distils over. When the heat has been kept up until no more liquid condenses, a brownish yellow residue the anhydrous lactic acid of Pelouze-C12 H10 010, remains. When the boiling is assisted by rough substances, the hydrated acid can be boiled at 390° F., and distilled without decomposition; without such aid, whilst a quantity distils over which augments with the temperature, the rest is converted at from 356° to 392° F. into an. hydrous acid. Anhydrous lactic acid is very sparingly soluble in boiling water, imparting to it a bitter taste. In the state of the above residue, it is a solid amorphous, brownish, yellow mass, fusible below 212° F., and on cooling is so tenacious that it may be drawn out into threads; its taste is extremely bitter; it is soluble in all proportions, in spirit and absolute alcohol. The anhydrous acid may be precipitated from this solution in flakes, which by degrees unite in the form of drops. Long boiling or exposure to damp air restores it to the ordinary condition. This is speedily effected by the alkalies and earths. A temperature of 464° F. produces no change in this anhydrous acid; at 482° F. decomposition commences, and at 500° F. it terminates. This decomposition furnishes carbonic oxide, and from 3 to 4 per cent. in volume of carbonic acid, aldehyde, lactide, and citraconic acid, with some reproduced lactic acid; no hydrocarbons were found, nor were any lactones or acetones, asserted by Pelouze to exist, observed. From 1 to 2 per cent. of carbon was left in the retort. When water is added to the distilled matter, to separate these substances, aldehyde and hydrated lactic acid are dissolved, and a transparent, yellowish, and at first very mobile oil subsides. After remaining some time in contact with water, this oil gradually decreases in quantity, disappearing entirely in a few days, leaving a few smeary crystals which also dissolve in time. This may be expedited by shaking or heating it with a large quantity of water. This oil is a mixture of hydrated lactic acid, citraconic acid, and lactide. No anhydrous acid distils over, as is proved by the fact that when the contents of the first receiver are solidified, * Annalen der Chemie. and then treated with alcohol, which does not dissolve the lactide, water precipitates no lactic acid from the solution. ALDEHYDE.-When the distilled matter, in the state of either liquid or crystalline paste is heated on a sand bath to 212° F., and the product received into anhydrous ether, kept cold, it yields, on ammonia being passed through it, aldehyde-ammonia. LACTIDE. The residue thus freed from aldehyde is a brownish liquid which generally solidifies into a crystalline paste, which is washed on a filter with cold absolute alcohol, and dried between folds of bibulous paper. Large crystals may be obtained by re-dissolving in a little boiling absolute alcohol, and setting apart to cool. That which does not crystallise by cooling is lost, being converted, by spontaneous evaporation and by heat, into common lactic acid. The crystals appear to belong to the rhombic system, and strongly resemble those of protosulphate of iron. Lactide cakes together at 248° F., and may be sublimed, but very slowly. Above this temperature it melts, sublimes more quickly, and at 500° F. furnishes the same products of decomposition as anhydrous lactic acid. Lactide, like that acid, acts on water and the alkalies and alkaline earths. It is re-converted into the hydrated acid. It is more soluble in boiling water than the anhydrous acid, and, on cooling, the greater part separates in small needles. It has no odor or taste, but, in assimilating water, it speedily acquires a very acid taste. Lactide, dried in vacuo, yielded C6 H4 04 50.00 49.87 5.67 44.46 5.56 44.44 100.00 100.00 CITRACONIC ACID is produced in only small quantity. The alcohol used for washing the crystals of lactic acid contains this acid and lactic acid; it is filtered and distilled; the liquid which passes over at 430° F. is saturated with carbonate of baryta, when the salt, which is quite insoluble in alcohol, subsides as a crystalline paste. This is dissolved in boiling water, and the citraconate separates on cooling in beautiful pearly lamine, which are obtained largest by concentrating the solution until a pellicle forms on the surface. The salt, dried in the air at 212°, lost five atoms of water. Thus dried, its composition was— Atoms. Carbon.... 10 Hydrogen 4 Oxygen.. 6 Baryta Found. Calcu —ཕིས--- ད 22.57 22.80 lated. 22.61 1.81 1.93 1.51 18.15 17.40 18.09 2 57.47 57.87 57.79 |