oxide, carrying over some sodium, burns at the end of the apparatus. This would all be very simple if the reaction of carbonic oxide on sodium near the condensing point did not complicate matters, producing a black, infusible deposit of Na2O and C, which on being melted always gives rise to a loss of sodium. The foregoing is the process as perfected by Donny and Mareska, Deville, and Tissier. Only a few improvements have been made, the most important are the following: R. Wagner* uses paraffin in preference to paraffin oil in which to keep the sodium after making it. Only pure paraffin which has been melted a long time on a water bath and all its water driven off can be used. The sodium to be preserved is dipped in the paraffin melted on a water bath and kept at no higher heat than 55°, and the metal is thereby covered with a thick coat of paraffin which protects it from oxidation, and may then be put up in wooden or paper boxes. When the metal is to be used, it is easily freed from paraffin by simply warming it, since sodium melts at 95° to 96° C. and the paraffin at 50° to 60°. The reduction of K2CO3 by carbon requires much less heat than that of Na2CO3, and, therefore, many attempts have been made to reduce potassium and sodium together, under circumstances where so * Dingler, 1883, p. 252. dium alone would not be reduced. Dumas* added some K2CO3 to the regular sodium mixture; and separated the sodium and potassium from each other by a slow, tedious oxidation. R. Wagnert made a similar attempt. He says that not only does the reduction of both metals from a mixture of K2CO3, Na2CO3, and carbon work easier than Na2CO3 and carbon, but even caustic soda (NaOH) may be used with K2CO3 and carbon. Also, the melting point of potassium and sodium alloyed is much lower than that of either one alone, in consequence of which their boiling point and the temperature required for reduction are lower. W. Weldon calculated the cost of sodium as seven to eight marks per kilo. The greater part of this is for retorts in which the operation takes place, and which are so quickly destroyed that the replacing of them forms half the cost of the metal. Compare with p. 172. The latest announcement of advance in making sodium is from New York City, and is thus described in a New York paper: "When sodium was reduced in price to $1.50 per pound, it was thought to have touched a bottom figure, and all hope of making it any cheaper seemed fruitless. This cheapening was not brought about * Handbuch der Angewandten Chemie, 1830, ii. 345. New York World, May 16, 1886. by any improved or new process of reduction, but was owing simply to the fact that the aluminium industry required sodium, and by making it in large quantities its cost does not exceed the abovementioned price. The retail price is now $4.00 per pound. The process now used was invented by Brünner, in 1808, and up to the present time nothing new or original has been patented except three or four modifications of his process which have been adopted to meet the requirements of using it on a large scale. Mr. H. Y. Castner, whose laboratory is at 218 West Twentieth Street, New York, has the first patent ever granted on this subject in the United States, and the only one taken out in the world since 1808. Owing to negotiations being carried on, Mr. Castner having filed applications for patents in various foreign countries, but not having the patents granted there yet, we are not at liberty to state his process fully. The metal is reduced and distilled in large iron crucibles, which are raised automatically through apertures in the bottom of the furnace, where they remain until the reduction is completed and the sodium distilled. Then the crucible is lowered, a new one containing a fresh charge is substituted and raised into the furnace, while the one just used is cleaned and made ready for use again. The temperature required is very moderate, the sodium distilling as easy as zinc does when being reduced. Mr. Castner expects to produce it at 25 cents per pound, thus solving the problem of cheap aluminium, and with it magnesium, silicon, and boron, all of which depend on sodium for their manufacture. Thus the production of cheap sodium means much more than cheap aluminium. Mr. Castner is well known in New York as a chemist of good standing, and has associated with him Mr. J. H. Booth and Mr. Henry Booth, both well known as gentlemen of means and integrity." 6 Mr. Benjamin, in a letter to the Engineering and Mining Journal,' gives the following details in addition to those above:* The pots used are cast iron, 8 inches in diameter and 14 inches deep. They are kept at bright red, or about 1000°, at which temperature the decomposition takes place. Whereas, by previous processes only one-third of the sodium in the charge is obtained, Mr. Castner gets nearly all, for the pots are nearly entirely empty when withdrawn from the furnace. Thus the great items of saving are, two or three times as much metal extracted from a given amount of salt, and cheap cast-iron crucibles used instead of expensive wrought-iron retorts. The following are the claims which Mr. Castner makes in his patent:—† Claim 1. In a process for manufacturing potassium or sodium, performing the reduction by diffus * Eng. and Min. Journ., May 29, 1886. U. S. Pat. No. 342,897, June 1, 1886. Hamilton Y. Castner, New York. ing carbon in a body of alkali in a state of fusion at moderate temperatures. 2. Performing the reduction by means of the carbide of a metal or its equivalent. 3. Mechanically combining a metal and carbon to increase the weight of the reducing material, and then mixing this product with the alkali and fusing the latter, whereby the reducing material is held in suspension throughout the mass of fused alkali. 4. Performing the deoxidation by the carbide of a metal or its equivalent. We learn later that Mr. Castner cokes a mixture of fine iron and gas-tar, grinds the coke, and uses this as the reducing material; caustic soda is used on account of its low fusing point. REDUCTION OF SODIUM BY ELECTRICITY. Mierzinski: In order to lower the cost of sodium efforts have been made to obtain it by means of electricity. Davy has shown that its production in this way is possible, for he first obtained the metal by electrolizing a solution of Na2CO3. P. Jablochoff uses the following arrangement to decompose NaCl or KCl : The arrangement is easily understood. The salt to be decomposed is fed in by the funnel into the kettle heated by a fire beneath. The positive pole evolves chlorine gas, and the negative pole evolves |