The beryllium chloride solution produced by either of these methods is mixed with any chloride of an alkali or alkaline earth metal (excepting that of magnesium or calcium), and is then evaporated to dryness, whereby a mixture of salts is obtained that is very fusible and a good conductor of electricity, and from which the beryllium may be extracted by one of the electrolytic methods that have been described as applicable to magnesium and lithium. A little sal-ammoniac should be added to the solution before evaporation, in order to prevent the formation of too much oxide by the decomposition of the beryllium chloride during that process. Concerning the electrolysis itself there is practically nothing to be said, except that it is conducted in the same manner and in the same class of apparatus as that of magnesium. It should be observed, however, that the melting point of the metal must be only just reached, and as little as possible exceeded, during the progress of the electrolysis, as the beryllium would otherwise alloy with iron. It is of importance, also, that the melting vessels should be made of good weld iron, on account of the somewhat higher temperature required for this process than that of carnallite reduction. Beryllium has not yet found any application in the arts. SECOND GROUP. SODIUM AND POTASSIUM. CHAPTER IV. SODIUM. Properties of the Metal.-Sodium (Na; atomic weight=23; specific gravity=0·974) is a white metal, the freshly cut surfaces of which exhibit a silvery white lustre; it is soft and may even be kneaded at ordinary temperatures. It melts at 95.6° C., and begins to vaporise at a clear red heat-i.e., at about 900° C. It is capable of alloying with the other alkali metals, and with some of the heavy metals. Of these alloys the amalgam, and the alloys with lead and tin, have found practical use in the arts. Sodium is capable of dissolving in anhydrous liquid ammonia, to which it imparts a blue colour. It oxidises very rapidly in the air, yet it may be melted without danger in a dry vessel over an open flame, provided that it is not heated much above its melting point. Once enkindled in air that is dry and free from carbonic acid, it burns with a yellow flame, and with the evolution of much heat, yielding the peroxide, Na2O2. It combines energetically, also, with the non-metals. It decomposes water even at the ordinary temperature, forming sodium hydroxide, and it must, therefore, be stored in liquids, such as petroleum, which contain no oxygen. As a metal which can decompose even water, it is very violently attacked by acids, forming salts which are, almost without exception, easily soluble in water. It is a powerful reducing agent, decomposing compounds of the metals, and even of many non-metals (CO2, SiO2, B2O3, &c.). 6 Occurrence in Nature. In nature it occurs only in the form of salts; as chloride, in rock-salt, NaCl; as fluoride, in cryolite, Ál,F. 6NaF; as sulphate, in Glauber's salt, Na2SO4. 10H0; as nitrate, in Chili saltpetre, NaNO,; as borate, in borax, Na,B,0,. 10H2O, and other borates; as carbonate, in soda, Na,CO. H2O, and in trona, (NaHCO3)2. Na,CO ̧ . 2H2O; as silicate, in felspar, &c. For the manufacture of soda compounds on the larger scale the chloride is mainly used; and the metal may be obtained either by a metallurgical reduction process from the carbonate or hydroxide, or by electrolysis from the fused chloride. 1. THE REDUCTION PROCESS. On the large scale, sodium was first* produced by distilling a mixture of anhydrous carbonate (calcined soda) and carbon ; whilst until recently the bulk of the metal was obtained by Castner's method,† which consisted in a reduction of the hydroxide by an intimate mixture of iron and carbon, thus : 3 NaOH + Fe. C2 = 3 Na + Fe + CO + CO2 + 3H. Netto has avoided the use of iron by causing fused caustic soda to drop upon a layer of heated carbon contained in an upright retort or reverberatory furnace. 2. ELECTROLYSIS. Davy's Experiments.-The electrolytic decomposition of the hydroxides of potassium and sodium led, as is well known, to the discovery of these metals. Davy§ thus described the apparatus which he employed for his research in this direction : 'By means of a stream of oxygene gas from a gasometer applied to the flame of a spirit lamp, which was thrown on a platina spoon containing potash, this alkali was kept for some minutes in a strong red heat, and in a state of perfect fluidity. The spoon was preserved in communication with the positive of the battery of the power of 100 of 6 inches, highly charged; and the connection from the negative side was made by a platina wire.” The reasons why this process cannot be used for the production of the alkali metals on a large scale need not be discussed at present; they will become evident from the discussion of later experiments. A modification of this method has been tried, in which a platinum dish containing mercury and a very concentrated solution of caustic potash is connected to the negative pole of a battery, and the resulting amalgam (formed by the combination of the mercury with the potassium produced by electrolysis) is distilled to separate the alkali metal. But the process is not practically workable, since the expenditure of electrical energy stands in most unfavourable proportion to the yield of metal. The descriptions, however, of both processes contained an item of the highest interest in applied electro-chemistry-namely, the use of a vessel made of a conducting material, and used simultaneously as the container for the electrolyte and as the pole of the decomposing cell. This circumstance cannot here be too strongly * Brunner, Schweigger's Journ., vol. xxi., p. 201; and St. Claire Deville, Ann. de Chem. et de Phys., 1852, vol. xliii., p. 5. + United States Patent 342,897, June 1, 1886. [Eng. Pat., 7,395, 1886.] German Patent 45,105 and 52,555. [Eng. Pat. 17,412, 1887.] § Phil. Trans. of 1808, pp.1, 333; 1810, p. 16. emphasised, since modern inventors are constantly endeavouring to pass off this idea as an original discovery. Watt's Process.-The first suggestion for the manufacture of alkali and alkaline earth metals originated with Charles Watt.* The patent specification ran as follows: "The second part of my invention consists of a mode of preparing or obtaining the metals of the alkalies and alkaline earths by the united action of electricity and heat. For performing this part of my invention by the united action of electricity and Fig. 19.-Watt's apparatus for the extraction of sodium. heat I employ a vessel of the form shown in Fig. 19, which is made of iron or other suitable material capable of bearing a full red heat. In this figure, A is the vessel, which should be at least half an inch thick and, if made of iron, previously to its being used should be coated over its exterior with clay or other substance to preserve it from the action of the fire; B, movable head for the collection of the metals; C, electrodes, with their attachments, e; D, flanges to support the vessel upon the furnace. The covered compartment, F, being that in which it is intended to eliminate the metals, is supplied with a carbon electrode, and the uncovered compartment is supplied with a gold electrode; but I wish it to be understood that I do not restrict myself to the particular form of apparatus, or to the material to be used for electrodes. The vessel is filled with dry saline matter, so that when it is in a state of fusion it shall reach the dotted line [the level shown in the figure]; the partition keeps the eliminated substances from reacting upon each other, and also excludes the air from the compartment in which the metal is eliminated, the access of which would cause the metal to be oxidised. The vessel is placed in a furnace where it can be subjected Eng. Pat. 13,755, Sept. 25, 1851. * to the action of a full red heat, and when the saline matter is in a state of fusion contact is made between the decomposing vessel and the apparatus supplying the electric current or currents, the intensity of which should, at least, be equal to that which would be supplied by ten cells of Daniell's battery arranged for intensity, but, of course, this depends upon the nature of the salt which is being decomposed. The fused salt is maintained at that temperature which will ensure the instantaneous volatilisation of the metal as it is eliminated, and a proper receiver (such a one as is usually employed for the preparation of such metals will answer) is connected air-tight with the narrow tube projecting from the head. The metal is received and preserved in any convenient fluid hydrocarbon. The salts which I usually employ are the chlorides, iodides, or bromides of the metals of the alkalies or alkaline earths." The salts which the inventor used may have been the haloid compounds of the alkali and alkaline earth metals, as he describes but neither before nor since the publication of that specification has it been possible to distil in an iron vessel the metals calcium, barium, or strontium, of which the melting points even approximate that of iron. Granted that he merely omitted by accident to explain in his specification that the electrodes were insulated not only from one another, but also from the iron crucible, the inventor must have used a remarkably refractory modification of gold if he succeeded in making from it an electrode which could be employed as the positive pole in a bath of fused alkaline chloride, and thus withstand the action of the nascent chlorine for a sufficiently long time to enable him to accomplish the decomposition of the alkaline halogen salts according to his usual methods. The patent was applied for on September 25, 1851, and granted on March 24, 1852. It is well known that in the summer of 1851, Bunsen succeeded in decomposing fused magnesium chloride into magnesium and chlorine by means of the electric current; and this classical research is described in vol. 2 (p. 137) of Liebig's Annalen for 1852. In outward form the apparatus used by Watt shows the closest agreement with that employed by Bunsen, and the difference between them lies in the fact that the latter, which was based on the results of Bunsen's investigation, fulfilled its purpose in every respect, whilst the former was altogether impracticable. The first success in the electrolytic treatment of the chloride of an alkali metal was obtained by Bunsen and Matthiessen with lithium chloride in the year 1854. This result has already been described (p. 34). Further improvements by Matthiessen, and afterwards by Linnemann, related specially to potassium, and will be referred to under that head. Jablochkoff's Process.-In spite of Bunsen's discoveries, the decomposition of sodium chloride appears to have involved |