By substituting these expressions in (2), we have

which is the sought equation. It is easy to see also that a deviation from the laws of Mariotte and Gay Lussac can be taken into consideration in this investigation as easily as in that of Hoppe.-Pogg. Ann. xcviii, 173, May, 1856.

3. On Ozone.-ANDREWS has communicated the results of a very elaborate and extended investigation of this subject, which forms an important contribution to our knowledge. The author in the first place repeated the experiments of Baumert, who arrived at the conclusion that ozone is a peroxyd of hydrogen, having the formula HOз. Andrews found that no two experiments led to the same constitution for this peroxyd, and finally discovered that the discrepancy was owing to a small quantity of carbonic acid which, without great care, is always mixed with electrolytic ozone. In Baumert's experiments the increase of weight of the apparatus was always greater than the weight of the ozone as deduced from its chemical action. Andrews found, however, that when the carbonic acid was completely removed these two quantities exactly agreed, so that it is proved that water is not a product of the decomposition of ozone, and therefore that this contains no hydrogen. In like manner it was shewn that no water is produced when ozone is decomposed by heat. The ozone obtained by electrolysis by the action of the electric spark and by the oxydation of phosphorus was found to be identical. Finally, it was found that ozone contained no nitrogen. The author concludes from his investigation that ozone is oxygen in an allotropic modification, and not a compound body as supposed by Schönbein, Williamson, and Baumert.-Phil. Tr. for 1855, quoted in Pogg. Ann. xcviii, 435, June, 1856. 4. Preparation of Aluminum.-BRUNNER has prepared aluminum directly from the fluorid instead of employing cryolite. The fluorid is prepared by dissolving alumina in fluohydric acid, or rather by condensing the acid in the alumina. The fluorid is then reduced by sodium in a hessian crucible, a layer of common salt being placed above the mixture. The yield is not stated.-Pogg. Ann. xcviii, 488.

5. On the conversion of carbonic oxyd into formic acid, and on the preparation of formic from oxalic acid.-BERTHELOT has found that when carbonic oxyd is heated in contact with hydrate of potash, forinate of potash is produced, the reaction being represented by the equation

2CO+KO, HO=C2HO3, KO.

This observation suggested to the author that formic acid might be produced easily and abundantly by making carbonic oxyd unite with water at the instant of its formation. As oxalic acid is decomposed by heating into carbonic acid, carbonic oxyd and water, it occurred to Berthelot that by heating this acid with some substance which should act by contact, the water and carbonic oxyd would unite to produce formic acid. Glyeerin was found to answer the purpose perfectly. The author introduces into a retort of 2 litres capacity, 1 kilogram of syrupy glycerin, 1 kilogram of commercial oxalic acid, and 100-200 grammes of water. A receiver is to be attached and the retort heated gently to 100° C.: carbonic acid is given off, and after from twelve to fifteen hours all the oxalic acid is decomposed, while a little weak formic acid has passed over. Half a liter of water is to be added to the matter in the retort and the whole distilled, water being added from time to time to make up the loss, until 6-7 liters of fluid have distilled over. The distillate then contains almost the whole of the formic acid, while pure glycerin remains in the retort, and may be used again and again. From 3 kilograms of oxalic acid the author obtained 1051 kilograms of formic acid, which is very nearly the theoretical amount. In this very simple and easy process it is only necessary to proceed slowly and not at too high a temperature, since when the mass reaches 190°-200° pure carbonic oxyd is given off. By this process carbonic oxyd may be prepared in a state of purity, the carbonic acid being first given off. The formic acid is pure and free from oxalic acid.-Comptes Rendus, xli, 955 and xlii, 447.

[Note.-Berthelot's process for preparing formic acid is so easy and elegant that this important substance can hereafter be furnished at a low price and in a state of purity. Its numerous and valuable applications in analytical chemistry will probably be speedily recognized; but it would be well worth while to examine its action in the place of acetic acid in photographic processes.-w. G.]

6. On the determination of chlorine by titrition.-With the view of rendering the end of the reaction more distinctly visible, MOHR has suggested the addition of a little neutral chromate of potash to the liquid containing the chlorid. The red color of the chromate of silver makes its appearance as soon as the last trace of chlorine is precipitated as chlorid of silver, and the end of the process is thus very distinct. Levol suggested the employment of phosphate of soda with the same object in view, but a much larger quantity of nitrate of silver solution must be added in this case to produce the yellow color, and the end of the reaction is therefore much less definite. In a second paper, Mohr has extended the method to the determination of many other substances by first converting them into chlorids and then determining the chlorine as above. [The method appears to give in many cases satisfactory results, but it is unfortunately inapplicable in the case of colored solutions. It is to be regretted that the ingenious author does not give a greater number of numerical data to prove the accuracy of the method in the various cases to which he applies it. We would also suggest that the practice of comparing the results obtained by a particular analytical method with theory by the difference should be abandoned, and that in all cases the percentage obtained should be stated.-w. G.]—Ann. der Chemie und Pharmacie, xcvii, 335, xcix, 197.

7. Reduction of aluminum from cryolite.-WÖHLER has found it advantageous in the preparation of aluminum to mix the finely pulverized and well dried cryolite with an equal weight of a mixture of 7 parts of chlorid of sodium and 9 of chlorid of potassium previously melted together and then finely pulverized. The mixture is to be introduced into a hessian crucible in alternate layers with slices of sodium, the separate layers being pressed strongly together. For every 50 grammes of the mixture, 8 or 10 grammes of sodium are to be used. The crucible must be previously strongly dried. It is then to be quickly heated to a white heat in a good furnace. At the moment of reduction a noise is heard and some sodium is volatilized which burns with flame. After this the heat must be kept up for a quarter of an hour to fuse the mass completely, and then allowed to cool. On breaking the crucible, the aluminum is found as a single white regulus, usually with a crystalline surface. In this way about 4 per cent of the weight of the cryolite is obtained, which is only about one-third of the aluminum in the mineral. The aluminum is free from silicon.-Ann. der Ch. und Pharm. xcix, 255, Aug. 1856.

8. Researches on the Fluorids.-FREMY has communicated the results of an elaborate investigation of the compounds of fluorine beginning as it were, de novo, from the very elements of the subject, and re-examining many points which have long been considered as settled. The author sums up his conclusions in the following words :

(1.) Fluohydric acid may be obtained from anhydrous acid in a state of purity by calcining, in a platinum apparatus, the fluohydrate of fluorid of potassium, previously dried. In this state the acid is gaseous at ordinary temperatures; it attacks glass and all silicious substances strongly, contrary to the assertions which have been made on this point of late years.

(2.) All the experiments described in this memoir, confirm the views of the constitution of fluohydric acid now received by all chemists, and shew that this acid really behaves like a hydracid.

(3.) It results from the general study of the fluorids which has been made, that these compounds may be divided into three classes, and that to each of these classes belongs an assemblage of important properties. The first class comprises the anhydrous fluorids which are comparable to the chlorids; the second the hydrated fluorids which behave, in all their reactions, like fluohydrates; in the third class we find the fluohydrates of fluorids which are true acid salts.

(4.) The anhydrous fluorids are remarkable for their stability; the hydrated fluorids are, on the contrary, unstable, and sometimes decompose even when they are dried in vacuo, disengaging fluohydric acid and leaving as a residue an oxyfluorid or oxyd.

(4.) The fluorids have a great tendency to unite to form double fluorids; this property belongs even to the insoluble fluorids. Thus these last compounds must never be prepared by double decomposition, because they always retain, in their state of double salt, a part of the soluble salt which has been employed in their preparation.

(6.) Hydrogen does not decompose all the fluorids by the aid of heat; thus it does not act on the fluorids of calcium: but it reduces with the greatest facility, the fluorids of lead, tin, &c. The reduction of the metallic fluorids by hydrogen, like those of lead and tin, which resist the action

of carbon, appears to demonstrate, in a positive manner that these compounds do not contain oxygen, and are really binary substances.

(7.) All fluorids, even those of potassium, sodium and calcium, are rapidly decomposed by the vapor of water.

(8.) Oxygen and chlorine, at a strong heat, decompose fluorid of calcium, and set free a gas which appears to be fluorine.

(9.) The vapor of sulphur does not act on fluorid of calcium, but this body is decomposed completely by the vapor of sulphid of carbon; there is formed in this case sulphid of calcium, and probably fluorid of carbon; the presence of silicious matters facilitates the reaction.

(10.) The analyses of the principal fluorids which are cited in this memoir, as those of the fluorids of potassium, sodium, calcium, tin, lead and silver, show that the equivalent of fluorine, determined by Berzelius, is exact.

(11.) All the anhydrous fluorids, when fused, may be decomposed by the galvanic battery, and disengage a gas which appears to be the radical of the fluorids.-Ann. de Chimie et de Physique, xlvii, 5, May, 1856.

9. On two new methods of producing Urea artificially.-NATANSON has succeeded in showing that carbamid and urea are identical. When carbonate of ethyl and ammonia are heated together in a sealed tube to 100° C., only urethan is formed; but at 180°, the urethan is converted, by the excess of ammonia into urea. When phosgene gas and ammonia are brought into contact, a white saline mass is formed, first studied in 1838, by Regnault, and which behaves like a mixture of carbamid and sal-ammoniac. Regnault did not succeed in separating the two substances or in proving that urea was present. This Natanson has done, and it is therefore proved that urea and carbamid are identical.

10. On Acetylamin.-NATANSON has more fully described this very interesting alkaloid, which he obtains by distilling the hydrated oxyd of acetyl-ammonium, which at a high temperature is decomposed into acetylamin and water, according to the equation

The decomposition begins at 150° C.; the acetylamin distils over at 220°, as a slightly yellow liquid of peculiar ammoniacal persistent smell. It boils at 218°, and is soluble in all proportions in water and alcohol, but not in ether. The density of its vapor was found to be 1.522-4 vols. By union with acids it forms salts of acetyl-ammonium, from which it is very remarkable that potash precipitates the hydrate of the oxyd of acetyl-ammonium and not acetylamin. The author describes an ethyl acetylamin and an anilin acetylamin-Ann. der Chemie und Pharmacie, xcviii, 287, 291, June, 1856.

W. G.

11. The Manufacture of Malleable Iron and Steel without Fuel, (Proc. Brit. Assoc., August, 1856; Ath. No. 1504.)-At a meeting of the British Association for the Advancement of Science, held at Cheltenham in August last, Mr. H. Bessemer read a highly interesting and important paper on the manufacture of malleable iron and steel without fuel. For two years

Mr. Bessemer has devoted his attention almost exclusively to the subject. Preliminary trials were made on from ten to twenty pounds of iron, and "although the process was fraught with considerable difficulty, it exhibited such unmistakeable signs of success," Mr. Bessemer observed, "as to induce me at once to put up an apparatus, capable of converting about seven hundred of crude pig iron into malleable iron in thirty minutes." "I set out with the assumption that crude iron contains about five per cent. of carbon; that carbon cannot exist at a white heat in the presence of oxygen without uniting therewith and producing combustion; that such combustion would proceed with a rapidity dependent on the amount of surface of carbon exposed: and, lastly, that the temperature which the metal would acquire would be also dependent on the rapidity with which the oxygen and carbon were made to combine, and consequently that it was only necessary to bring the oxygen and carbon together in such a manner that a vast surface should be exposed to their mutual action, in order to produce a temperature hitherto unattainable in our largest furnaces.

With a view of testing practically this theory, I constructed a cylindrical vessel of three feet in diameter and five feet in height, somewhat like an ordinary cupola furnace, the interior of which is lined with fire bricks; and at about two inches from the bottom of it I insert five tuyère pipes, the nozzles of which are formed of well-burned fire clay, the orifice of each tuyère being about three-eights of an inch in diameter; they are so put into the brick lining (from the outer side) as to admit of their removal and renewal in a few minutes when they are worn out. At one side of the vessel, about half way up from the bottom, there is a hole made for running in the crude metal, and on the opposite side there is a tap-hole stopped with loam, by means of which the iron is run out at the end of the process. In practice this converting vessel may be made of any convenient size, but I prefer that it should not hold less than one, or more than five tons, of fluid iron at each charge. The vessel should be placed so near to the discharge hole of the blast furnace as to allow the iron to flow along a gutter into it; a small blast cylinder will be required capable of compressing air to about 8lb. or 10lb. to the square inch. A communication having been made between it and the tuyères before named, the converting vessel will be in a condition to commence work; it will, however, on the occasion of its first being used after relining with fire-bricks, be necessary to make a fire in the interior with a few baskets of coke, so as to dry the brickwork, and heat up the vessel for the first operation, after which the fire is to be all carefully raked out at the tapping-hole, which is again to be made good with loam. The vessel will then be in readiness to commence work, and may be so continued, without any use of fuel, until the brick lining in the course of time, becomes worn away, and a new lining is required. I have before mentioned that the tuyères are situated nearly close to the bottom of the vessel; the fluid metal will therefore rise some eighteen inches or two feet above them.

It is therefore necessary, in order to prevent the metal from entering the tuyère holes, to turn on the blast before allowing the fluid crude iron to run into the vessel from the blast furnace. This having been done, and the fluid iron run in, a rapid boiling up of the metal will be heard