CHEMISTRY. 



107 



the production of metallic sodium and potas- 

 sium, which has been mentioned in previous 

 volumes of the "Annual Cyclopedia,'' has 

 proved to be practicable and successful. A 

 more detailed description of the process than 

 we have hitherto given is the following : " The 

 mineral known as 'purple ore,' an oxide of 

 iron, is heated to a temperature of 500 C., 

 and at the same time a mixture of carbonic 

 oxide and hydrogen is poured over it. By 

 this the oxide of iron is changed into metal- 

 lic iron, which remains in the state of a fine 

 powder. This powder is mixed with melt- 

 ed pitch, and the whole is allowed to cool. It 

 is next broken into lumps of about the size of 

 bricks, and these are heated in large crucibles, 

 and converted into coke. This coke is found 

 to contain a definite quantity of iron and car- 

 bon, which can not be separated again by me- 

 chanical means. It is next powdered finely, 

 and added in proper proportions to the hydrate 

 of potash or soda, and the mixture is gently 

 heated for about thirty minutes in a retort of 

 cast-steel or cast-iron, whereby it is fused and 

 made to give off large quantities of hydrogen 

 gas. When the bulk of this gas has disap- 

 peared, the reaction proceeds with less vio- 

 lence ; and the retort is then placed in a hotter 

 furnace where the temperature rises to about 

 ^ : JO C. The sodium or potassium distills over 

 very quickly, and in about ninety minutes the 

 operation is complete. Great care is taken 

 that no carbonic-acid gas should be produced 

 during the distillation of the metal, because 

 this gas is the cause of the formation of the 

 explosive compound. This is practically pos- 

 sible without adopting any other precaution 

 than that of using a quantity of the coke slight- 

 ly less than the theoretical amount." 



0. A. Crampton and T. 0. Trescot describe 

 a process for the estimation of carbonic acid in 

 beer. The analysis is difficult in the case of 

 beer in casks or kegs, on account of the im- 

 possibility of preventing the loss of carbonic 

 acid in drawing the beer, but is easier with 

 bottled beer. A champagne tap is used for 

 drawing the gas. A difficulty arising from 

 the stoppage of the tube by the accumulation 

 of bubbles was obviated by connecting the 

 champagne tap with an Eslenmeyer flask, in 

 the broad bottom of which the bubbles are 

 broken. This is connected with a U-tube 

 filled with sulphuric acid, and this with a cal- 

 cium-chloride tube and then a soda-lime tube 

 to absorb the dried carbonic acid. The drawing 

 of the gas through the tap is assisted by heat- 

 ing it to 80 C. after it has ceased to flow spon- 

 taneously. The gas is collected and absorbed 

 in the soda-lime tube; and the increase in 

 weight of the latter after the experiment gives 

 the amount of carbonic acid in the beer. 



II. B. Cornwall, analyzing butter for the de- 

 tection of artificial coloring- matters, extracts 

 annotto by the ethereal process. The dry, 

 yellow, or slightly-orange residue of this sub- 

 stance turns blue or violet-blue with sulphuric 



acid, then quickly green, and finally brownish, 

 or to a violet variable according to the purity 

 of the extract. Saffron, which can be extract- 

 ed in the same way, differs from annotto very 

 decidedly ; the most important difference is in 

 the absence of the green coloration. Genuine 

 butter, free from foreign coloring-matter, im- 

 parts at most a very pale-yellow color to the 

 alkaline solution ; but it is important to note 

 that a mere green coloration of the dry residue 

 on the addition of sulphuric acid is not a .cer- 

 tain indication of annotto ; for the author has 

 obtained from genuine butter, free from for- 

 eign coloring-matter, a dirty-green coloration, 

 but not preceded by any blue or violet-blue 

 tint. Turmeric is easily identified by the brown- 

 ish to reddish stratum that forms between the 

 ethereal fat solution and the alkaline solution 

 before they are intimately mixed. It may be 

 better recognized by carefully bringing a very 

 slightly alkaline solution of ammonia in alcohol 

 beneath the fat solution, and then gently agi- 

 tating the two for a moment. 



The brothers 0. and A. Brice, of Paris, ob- 

 tain oxygen in quantities for economical use 

 by utilizing the property of barium oxide, 

 BaO, of absorbing oxygen from the atmos- 

 phere at a moderate heat, whereby the super- 

 oxide, BaOa, is formed, and giving it out again 

 when heated to a higher temperature. During 

 the oxidating process the nitrogen is pumped 

 into a second system of retorts containing a 

 baryta coke, formed by mixing caustic baryta 

 and charcoal-dust with tar, whereby a cyanide 

 of barium is formed, and then converted by 

 treatment with steam at 300 C. into ammonia, 

 carbonic acid, and regenerated baryta. Baryta 

 is obtained for this purpose by treatment of 

 the nitrate by a patented process. 



H. Moissan has isolated fluorine by exposing 

 anhydrous hydrofluoric acid to a strong electric 

 current, using platinum for the negative, and a 

 mixture of nine parts of platinum and one part 

 of iridium for the positive electrode, and re- 

 enforcing the hydrofluoric acid at a certain mo- 

 ment with hydrofluorate of potash. Hydrogen 

 appeared at the negative electrode, and at the 

 positive, fluorine, as a colorless, strongly-smell- 

 ing gas. In it, silicon burned with a bright 

 glow, producing fluosilicic acid, as did also, like- 

 wise with light, and producing their respective 

 fluorine compounds, boron, phosphorus, arsenic, 

 antimony, sulphur, and iodine. Water was 

 decomposed with the formation of hydrofluoric 

 acid and ozone; iodine was separated from 

 potassium iodide. The gas acted less vigor- 

 ously upon the metals, probably because the 

 resultant coating of fluoride protected the rest 

 of the metallic substance ; and was inert as to 

 carbon. Many organic substances were strongly 

 attacked, and some, including alcohol, ether, 

 benzine, petroleum, and turpentine oil, with 

 ignition. After some time, the fluorine and 

 hydrogen again came in contact, when they 

 were reunited, with detonation. 



MM. Colson and Gauthier describe a new 



