270 FLUORINE. 



care, luis beeu fixed by means of cork in a cylindrical glass vessel and 

 surrounded by methyl chloride. IJ\) to the moment of introducing the 

 hydrofluoric acid the exit tubes have been connected with exsiccators 

 containing fused potash. The hydrofluoric acid is brought into this 

 little apparatus by inserting one of the lateral tubes into the receiver 

 in which it is condensed. 



When a determinate volume of liquid hydrofluoric acid has been col- 

 lected in the platinum apparatus, and cooled by gently boiling methyl 

 chloride to a temperature of — 23° C, the current from twenty-five large 

 Bunsen cells, mounted in series, is passed through it. An ampere 

 meter placed in the circuit enables us to take account of the intensity 

 of the current. 



In order to make the acid a conductor there is added to it before the 

 experiment a little of the dried and fused fluohydrate of potassium 

 fluoride, about 2 grams to 10 cubic centimeters of the liquid. Under 

 these conditions the decomposition takes place continuously, and we 

 obtain, at the negative pole, a gas which burns wiih a colorless flame, 

 and which has all the characteristics of hydrogen. At the positive pole 

 there is a colorless gas of a very disagreeable, penetrating odor, 

 resembling that of hypochlorous acid, and irritating to the mucous 

 membrane of the throat and the eyes. The new gas is endowed with 

 very energetic properties — fur instance, sulphur inflames upon contact 

 with it. 



Phosphorus takes fire in the gas and yields a mixture of oxyfluoride 

 and fluoride. Iodine combines with it, giving a pale flame and losing- 

 its color. Powdered arsenic and antimony combine with fluorine incan- 

 descently. 



Crystallized silicon, even when cold, kindles immediately upon con- 

 tact with the gas, and burns with much brilliancy, sometimes giving 

 off sparks. The product is silicon fluoride, which can be collected over 

 mercury and clearly identified. 



Pure boron ignites also, giving fluoride of boron. Amorphous carbon 

 becomes incandescent upon contact with fluorine. In order to make 

 these difi'erent experiments it suffices to put the solid substance in a 

 small glass tube, which is brought close to the extremity of the plati- 

 num tube from which the fluorine emerges. We can also repeat the 

 experiments by putting small fragments of the solid bodies to be stud- 

 ied upon the cover of a platinum crucible held near the opening of the 

 exit tube. 



The gas decomposes water in the cold, yielding hydrofluoric acid and 

 ozone: it ignites carbon disulphide, and when collected in a platinum 

 crucible containing carbon tetrachloride it produces a continuous lib- 

 eration of chlorine. 



Fused potassium chloride is attacked in the cold with disengage- 

 ment of chlorine. In presence of mercury the gas is completely 

 absorbed, forming light-yellow mercurous fluoride. Potassium and 



