the family of Lavoisier, and in part from notes made by this unfortunate savant during his journeys, which, as well as his laboratory notes and other papers, were happily preserved, they having been long in the hands of Arago to whom they were confided by the daughter of Lavoisier.

3. Magnesium Light.-The remarkable properties of magnesium light are now familiar to all. (See this Jour., xl, 287.) Some facts have been recently observed that are not yet generally known. As regards its chemical effects, this light is well fitted to render luminous phosphorescent bodies, as was fully ascertained by Mr. Chautard in the month of January, 1865. This is now a lecture-room experiment. Take a series of wide tubes enclosed in a box and filled with phosphorescent substances. All these tubes are white; but when struck by the magnesium light each becomes phosphorescent, taking its own special color. About a year since, also, Mr. Lallemand discovered that a mixture of chlorine and hydrogen will explode under the influence of magnesium light; and, moreover, that this explosion does not take place in darkness, nor under the influence of the red or yellow rays, as had already been remarked for common light by Gay Lussac and Thenard.

Magnesium ignites even in the vapor of water, when it is brought in contact with it in a tube containing magnesium heated over an alcohol lamp; the metal burns with brilliancy, disengaging the hydrogen. Under the same circumstances zinc will not burn except at a much higher temperature. This observation has just been made by Messrs. Deville and Caron; these chemists satisfied themselves that magnesium, when cold, decomposes water in the presence of the feeblest acids, even of carbonic acid.

If this metal were not so expensive its light could be applied to numerous uses. A recent invention of an Italian, Mr. Carlevaris, may perhaps prove to be a successful application of it. In place of the metal, he takes the chlorid of magnesium, which he exposes to a jet of ordinary illuminating gas and atmospheric air with a tenth part of oxygen. The light thus produced is very brilliant and appears to answer admirably for the production of photographic images, or for magnifying them.

At first Mr. Carlevaris used magnesia, and also carbonate of magnesia. But he found afterwards that the chlorid gave better results.

4. New facts concerning Thallium. Position of Thallium in classification. Mr. Crookes persists in arranging thallium near lead (Journ. Chem. Soc., April, 1864), while Mr. Lamy is equally decided in placing it among metals of the 1st section. Each cites facts favorable to his own views. In a review of all these facts and considerations in the Journal of Chemistry and Pharmacy (Nov. 1865) I have shown the possibility of resolving the question by placing thallium with the alkali metals, but also including with it lead and silver. This opinion confirms a theory brought forward twenty years since by Mr. Baudrimont, who even then ranked lead with barium. Now that we have an alum with a base of oxyd of silver, isomorphous with the alum of thallium, that of potassium, etc., there is less objection to putting in the same group all these metals, although in other respects they are quite dissimilar. The facts mentioned tend to show that thallium should be considered as establishing a point of union between the alkali metals on one side, and lead and silver on the other.

5. Bromo-thallic and Iodo-thallic acids.-After having established the fact that thallium forms with bromine and iodine the compounds Tl Br3, TI 13, I have found also that these compounds act like acids and form with the bromids and alkaline iodids, bromo-thallates and iodo-thallates, perfectly definite and crystallizable (Feb. 1864). These compounds are isomorphous with one another. Further, the acids Ti Cl3 and TI Br3 are capable of combining with several equivalents of ether. TI3 however does not so combine under these circumstances; it has not yet been isolated. Comptes Rendus, March, 1864.

6. Separation of lead and of bismuth by means of Bromo-thallates.— There has been till now no process known by which lead can be easily separated from bismuth. The alkaline bromo-thallates, of which I am speaking, furnish us with the means. In fact, when these salts are pure and free from chlorids or from bromids in excess, they do not act upon the salts of lead, while they yield with the salts of bismuth a white precipitate of bromo-thallate of bismuth. This white precipitate is soluble in a concentrated solution of sal-ammoniac. The reagent employed is one of the salts which I have described.

Br3 Tl, Br K+4HO; rhombic tables.

Br3 Tl, Br Am+SHO; crystallized in yellow needles.
Br3 Tl, Br Am+4HO, isomorphous with the first,

Having a limpid solution containing a salt of lead, as well as one of the bromo-thallates of which we have been speaking, it is sufficient to add some nitrate of bismuth to obtain immediately a marked reaction; all the bismuth is found in the precipitate when a sufficient quantity of the bromothailate has been employed.-Journal de Pharm. et de Chim., [4], ii, 218.

7. On detonating Antimony. This metal, as Mr. Gore has observed, attaches itself to the negative pole of a pile, when a solution of the chlorid, bromid or iodid is subjected to voltaic action. Various explanations have been given of this peculiarity, and it is not surprising that it has been attributed to catalysis, or to a peculiar condition of the antimony, In preparing this metal, I have found that the deposit of detonating antimony is formed only when operating with a compound containing chlorine, bromine or iodine; and that, moreover, detonating antimony always contains a sensible proportion of a halogen element. I hence conclude that detonating antimony is not a metal in a peculiar condition, but that it owes its explosive property to the presence of a small quantity of a compound similar to chlorid of nitrogen. This explanation, which I first proposed in 1858, is in no way contrary to facts, for chlorid of nitrogen also is produced under the influence of the voltaic pile.

We may then expect to see formed an explosive phosphorus, arsenic, or bismuth, because of the analogies between these elements and nitrogen or antimony.

8. Existence of chlorids corresponding to peroxyds.—In treating peroxyd of manganese with hydrochloric acid, free chlorine is obtained, in accordance with the equation MnO2+2C1H=2HO+Mn Cl+Cl (1.)

The treatises add that half the chlorine is set free because the compound corresponding to MnO2, that is to say the perchlorid MnCl2, does not exist; for if so the equation would be MnO2+2CIH=2HO+ MnO2 (2), with consequently, no free chlorine.

I have ascertained that the perchlorid Mn Cl2 can really be obtained, and that the same is true of Mn Br2 and MnI2. Various processes lead to this conclusion; the most important requisite is to use as little water as possible. On shaking in a tube, well cooled, peroxyd of manganese with a little ether saturated with chlorhydric gas, a liquid is immediately obtained of a green color which is nothing but a compound of Mn Cl2 with C4 H5O. This compound is rapidly reduced and discolored by SO2, S, Ph, Al, Fe, Zn, PbS, SbS3, &c.; it takes moistures from the air, and speedily undergoes alteration, giving out the gas CIH. In the presence of much ether it dissolves, changes color and becomes red, like mineral chameleon.

To perform the experiment in a public lecture, a little MnO2 in powder is put into a white dish, and ether saturated with chlorhydric gas is poured upon it. It is stirred with a glass rod, and immediately the liquid becomes of a beautiful green color.

In default of ether saturated with CIH, chlorhydric acid in a saturated aqueous solution may be used; in this case the liquid becomes at first brown, but it turns green when ether is added. It is a very beautiful experiment.

The

The bromohydric and iodohydric acids act in the same manner. products, however, are less stable than those obtained with MnO2. The sesquioxyd of manganese gives similar results. At the same time I ascertained that the formation of the sesqui-iodid, Fe2 13, whose existence has been denied by Gmelin and others, is nevertheless possible when iodohydric gas is made to act upon sesquioxyd of iron and anhydrous ether in a very cold tube. Its stability is not great.

In France the perchlorids (perchlorures) bear the name of singulochlorids (chlorures singuliers) conforming to the denomination of singulooxyds which Dumas has imposed upon peroxyds, such as MnO2, PbO2, BaO2, &c.-Annales de Chimie et de Physique, [4], v, 161.

9. Combinations of Boron with the Halogens.-Anhydrous boracic acid dissolved in absolute alcohol, and treated with a current of CIH, or BrH, acts like the oxyd just spoken of; that is, its oxygen separates itself from the chlorine and bromine so that it forms chlorid or bromid of boron, which remains in combination with the organic molecule.

Chlorid of boron, Bo C13.-A solution of boracic acid in absolute alcohol absorbs with avidity the anhydrous gas CIH, and becomes oily. It fumes in the air. Water decomposes it, producing boracic acid, chlorhydric acid, and alcohol. It is not volatile. Although the liquid appears to be only a solution, it has a definite composition, expressed by the formula 3Bo 03, 3CIH+5(C4H5O). Heated, it emits torrents of the gas CIH, containing boron; the thermometer rapidly rises to 85° C. The residue is boracic acid. The volatile part is chloro-boracic ether, BoO3+5(C⭑H3O)+910.

With boracic acid, anhydrous ether, and dry CIH, analogous results are obtained, if heat at 100° be employed.

Bromid of boron, Bo Br3.-The acid BrH gives very nearly the same results. The ethereal liquid collected at 115° C. has the formula Bo Br3+ 13(C4H6O2)+3HO; or rather Bo Br3+13(C4H50)+16HO.

All these ethers are alike in their acrid taste, the white fumes which they emit, and which contain some boracic acid, the accompanying compounds, and finally in their property of coloring dry tumeric brown, a property belonging also to dry chlorhydric gas.

These new compounds act with MnO2 like ether charged with CIH; that is to say, it transforms it into MnCl2 or MnBr2; the sesquioxyds are equally attacked by it.

10. Acclimatization of the Ostrich.-In my letter of April, 1861, I have spoken of the attempts to acclimatize the Ostrich. The Society of Acclimatization continues to watch and encourage these efforts. They now begin to hope that even in temperate climates, the Ostrich may figure among the useful animals. The following are the facts upon which these hopes are founded. We have already seen that these animals can repro duce in captivity, but as yet only in the warm regions of Europe, at Florence, Marseilles, Madrid, or in Algiers. This year, however, a birth of ostriches has taken place in the cooler region of Grenoble, in the garden of acclimatization of the Regional Society of the Alps.

The ostriches at the time of breeding were kept in a chamber. After 46 days two young ones appeåred, to which the female seemed as devoted as she had been indifferent to the eggs. On this occasion, as has been before observed, the little ones placed themselves only under the male, and received no nourishment from the parents.

After the results obtained in Spain, and since in England, we may hope also to acclimatize the Cassowary.

11. Acclimatization of Salmon in Australia.-After many unsuccessful attempts, arising from the eggs of the Salmon being hatched on the journey, they have at last succeeded in acclimatizing the Salmon in the fresh waters of Australia, and simply by retarding the hatching by keeping them in ice. We have already spoken of these attempts. The Society of Acclimatization at Paris learn from Mr. Ed. Wilson, President of the Society of Acclimatization of Victoria (Australia), that the young fish hatched in 1864 have done wonderfully well, and encourage the belief that their acclimatization and reproduction are assured facts.

12. Vitality of the Salmonida.-On this occasion, we may recall the results of some experiments that Mr. Millet has undertaken on the circulation in young Salmonidæ, such as the European Salmon, Trout, Greyling (Thymallus), and Coregonus. The result is very important to practical pisciculture.

In the earlier state, the vitality of the Salmonidae has as its inferior limit -2° C, and as the higher +30° C. With trout, and with the Salmonidæ in general, the necessities of respiration increase with the temperature. Water in which the fish live should be much more aërated, or more frequently renewed, when the temperature is above +15° C. than when it remains below +10° C.

The transportation of embryonic eggs and of young Salmonidæ requires much less air, or less water, at a low temperature, than at a high temperature. The fertilized eggs will bear long journeys, and may be carried great distances, if kept moist at a temperature a little above zero. The most favorable temperature for the development of the young Salmonidæ is between 10° and 15° C.

13. On the origin of terrestrial magnetism.-Under this title I have pointed out in this Journal in 1854 (xvii, 116, xviii, 386, xix, 104,) that terrestrial magnetism has no other origin than that of the rotation of the earth; that the sun is a magnet, and also derives its magnetism from its rotation. I recall these facts with reference to a note on this subject published in this Journal, vol. xxxviii, p. 420, Nov. 1864.

14. BIBLIOGRAPHY.-Archives of the Scientific Commission to Mexico, vol. i. Paris, Imperial Press. 1865.-Besides the regulations organizing the Scientific expedition, decreed Feb. 27th, 1864, this first volume contains a series of memoirs and of instructions, of the highest interest, on the following subjects: On Anthropology, by M. Quatrefages; on Zoology by Milne Edwards; on Botany by Decaisne; on Geology and Mineralogy by Ch. Deville. There are also memoirs and reports by Messrs. Milne Edwards, Boussingault and Vaillant on different interesting Mexican subjects; and others by Baron Gros, &c., relate to the exploration of ancient monuments in Mexico and Xochicalco; on the manufacture of Aztec knives, in obsidian; on the ruins of Yucatan, and finally on different subjects connected with medicine, metallurgy, meteorology, natural history, and the agriculture of Mexico.

15. Memoirs on the use of iodine and potassium in treating diseases from lead and mercury, and syphilis; by M. MELSENS. Paris, 1865. lu 8vo. The object of this memoir is to show by experiments, the importance of iodine and potassium in the treatment of the diseases above mentioned. This treatment is founded on the power of iodine and potassium to render soluble, and eliminate from the state of double iodids, the metallic compounds which have been introduced into the organism. The facts cited by Mr. Melsens, and the cures performed appear conclusive. He gives also a brief review of experiments in Austria in the mercury mines of Idria, and in the Wieden hospital at Vienna.

16. Figuier: La Plante.-Botany illustrated, for popular use. One large vol. in 8vo, with handsome plates and beautiful drawings.-A work well adapted to the parlor from the facility with which the dryest details of natural history are made intelligible to the uninitiated.

17. Victor Meunier; Science and its followers in 1864. 2 vols. 12mo. -A critical review of the labors and achievements of men of science, written with much sprightliness and force. Among the principal questions treated are" Aërial navigation, spontaneous generation, lake dwellings," &c., &c.

18. Review of Medical Hydrology, both French and foreign, 8th year.— This review is published every two months at Strasbourg, under the direction of Dr. Aimé Robert, chief editor. It treats of whatever relates to mineral waters, and also is occupied naturally with hydropathy, etc.

19. OBITUARY.-Dr. LEREBOULLET. While bringing this letter to a close the sad intelligence reaches us of the death of the geologist Dominique Auguste Lereboullet. He was Dean of the Faculty of Sciences at Strasbourg, and at the same time Professor, with great success, of zoology. He was also Director of the Museum of Natural History in that city. Time fails us to notice his life, which was devoted to constant study, or to speak of his labors, which have given him all kinds of recompense and a high rank among men of science. He died at Strasbourg, Oct. 6th, 1865, at the age of 61. He had been more than 40 years in the Faculty of which he was Dean.