626 



NATURE 



[October 29, 1891 



•violent detonations. A curious reaction also occurs when 

 fluorine is similarly passed into a 50 per cent, aqueous 

 solution of hydrofluoric acid itself, a flame being pro- 

 duced in the middle of the liquid, accompanied by a 

 series of detonations. 



Nitric acid vapour reacts with great violence with 

 fluorine, a loud explosion resulting. If fluorine is passed 

 into the ordinary liquid acid, each bubble as it enters 

 produces a flame in the liquid. 



Ammonia gas \'=> decomposed by fluorine with forma- 

 tion of a yellow flame, forming hydrofluoric acid and 

 liberating nitrogen. With a solution of the gas in water, 

 ■each bubble of fluorine produces an explosion and flame, 

 -as in case of hydriodic acid. 



Phosphoric anhydride, \v\\tr\ heated to lowredness, burns 

 with a pale flame in fluorine, forming a gaseous mixture of 

 fluorides and oxyfluoride of phosphorus. Peniachloride 

 and trichloride of phosphorus both react most energetic- 

 ally with fluorine, instantly producing a brilliant flame, 

 and evolving a mixture of phosphorus pentafluoride and 

 •free chlorine. 



Arsenioiis anhydride also affords a brilliant combus- 

 tion, forming the liquid trifluoride of arsenic, AsFg. This 

 -liquid in turn appears to react with more fluorine with 

 considerable evolution of- heat, probably forming the 

 pentafluoride, AsFg. Chloride of arseitic, AsClg, is con- 

 verted with considerable energy to the trifluoride, free 

 chlorine being liberated. 



Carbon bisulphide inflames in the cold in contact with 

 fluorine, and if the fluorine is led into the midst of the 

 liquid a similar production of fl ime occurs under the sur- 

 face of the liquid, as in case of nitric acid. No carbon is 

 •deposited, both the carbon and sulphur being entirely 

 converted into gaseous fluorides. 



Carbon tetrachloride, as previously mentioned, reacts 

 •only very slowly with fluorine. The liquid may be satu- 

 rated with gaseous fluorine at 1 5°, but on boiling this liquid 

 a gaseous mixture is evolved, one constituent of which is 

 -c.xrbon tetrafluoride, CF4, a gas readily capable of absorp- 

 tion by alcoholic potash. The remainder consists of 

 another fluoride of carbon, incapable of absorption by 

 potash, and chlorine. A mixture of the vapours of carbon 

 •tetrachloride and fluorine inflames spontaneously with 

 detonation, and chlorine is liberated without deposition of 

 carbon. 



Boric anhydride is raised to a most vivid incandescence 

 by fluorine, the experiment being rendered very beautiful 

 by the abundant white fumes of the trifluoride which are 

 liberated. 



Silicon dioxide, one of the most inert of substances at 

 the ordinary temperature, takes fire in the cold in con- 

 tact with fluorine, becoming instantly white-hot, and 

 rapidly disappearing in the form of silicon tetrafluoride. 

 The chlorides of both boron and silicon are decomposed 

 by fluorine, with formation of fluorides and liberation of 

 ■chlorine, the reaction being accompanied by the production 

 of flame. 



ACTION OF FLUORINE UPON METALLIC COMPOUNDS. 



Chlorides of the metals are instantly decomposed by 

 fluorine, generally at the ordinary temperature, and in 

 certain cases, antimony trichloride for instance, with the 

 appearance of flame. Chlorine is in each case liberated, 

 and a fluoride of the metal formed. A few require heating, 

 when a similar decomposition occurs, often accompanied 

 by incandescence, as in case of chromium sesquichloride. 



Bromides and iodides are decomposed with even 

 greater energy, and the liberated bromine and iodine 

 burn in the fluorine with formation of their respective 

 fluorides. 



Cyanides react in a most beautiful manner with fluo- 

 rrine, the displaced cyanogen burning with a purple flame. 

 Potassium ferrocyanide in particular affords a very pretty 



NO. I 148, VOL. 44] 



experiment, and reacts in the cold. Ordinary potassium 

 cyanide requires slightly warming in order to start the 

 combustion. 



Fused potash yields potassium fluoride and ozone. 

 Aqueous potash does not form potassium hypofluorite 

 when fluorine is bubbled into it, but only potassium 

 fluoride. Lime becomes most brilliantly incandescent, 

 owing partly to the excess being raised to a very high 

 temperature by the heat developed during the decom- 

 position, and partly to the phosphorescence of the calcium 

 fluoride formed. 



.S"«/^/«<y^.y of the alkalies and alkaline earths are also 

 immediately rendered incandescent, fluorides of the metal 

 and sulphur being respectively formed. 



Boron nitride behaves in an exceedingly beautiful man- 

 ner, being attacked in the cold, and emitting a brilliant 

 blue light which is surrounded by a halo of the fumes of 

 boron fluoride. 



Sulphates, nitrates, and phosphates generally require 

 the application of more or less heat, when they too are 

 rapidly and energetically decomposed. Calcium phos- 

 phate is attacked in the cold like lime, giving out a 

 brilliant white light, and producing calcium fluoride and 

 gaseous oxyfluoride of phosphorus, POF3. Calcium car- 

 bonate a.\%o becomes raised to brilliant incandescence when 

 exposed to fluorine gas, as does also normal sodium 

 carbo7iate ; but curiously enough the bicarbonates of the 

 alkalies do not react with fluorine even at red heat. 

 Perhaps this may be explained by the fact that fluorine 

 has no action at available temperatures upon carbon 

 dioxide. 



ACTION OF FLUORINE UPON A FEW ORGANIC 

 COMPOUND.S. 



Chlorofor?n.~V<[hen chloroform is saturated with 

 fluorine, and subsequently boiled carbon tetrafluoride, 

 hydrofluoric acid and chlorine are evolved. If a drop of 

 chloroform is agitated in a glass tube with excess of 

 fluorine, a violent explosion suddenly occurs, accompanied 

 by a flash of flame, and the tube is shattered to pieces. 

 The reaction is very lively when fluorine is evolved in the 

 midst of a quantity of chloroform, a persistent flame burns 

 beneath the surface of the liquid, carbon is deposited, and 

 fluorides of hydrogen and carbon are evolved together 

 with chlorine. 



Methyl chloride\s decomposed by fluorine, even at - 23", 

 with production of a yellow flame, deposition of car- 

 bon, and liberation of fluorides of hydrogen and carbon 

 and free chlorine. With the vapour of methyl chloride, 

 as po'nled out in the description of the electrolysis, violent 

 explosions occur. 



Ethyl alcohol vapour at -once takes fire in fluorine 

 gas, and the liquid is decomposed with explosive violence 

 without deposition of carbon. Aldehyde is formed to a 

 considerable extent during the reaction. 



Acetic acid and benzene are both decomposed with 

 violence, their cold vapours burn in fluorine, and when the 

 latter is bubbled through the liquids themselves, flashes of 

 flame, and often most dangerous explosions, occur. In the 

 case of benzene, carbon is deposited, and with both 

 liquids fluorides of hydrogen and carbon are evolved. 

 Aniline likewise takes fire in fluorine, and deposits a large 

 quantity of carbon, which, however, if the fluorine is in 

 excess, burns away completely to carbon tetrafluoride. 



Such are the main outlines of these later researches of M. 

 Moissan, and they cannot fail to impress those who read 

 them with the prodigious nature of the forces associated 

 with those minutest of entities, the chemical atoms, as 

 exhibited at their maximum, in so far as our knowledge 

 at present goes, in the case of the element fluorine. 



A. E. TUTTON. 



