618 Scientific Proceedings^ Royal Dublin Society. 



Phosphohus. 



It was extremely difficult to obtain a spectrum of phosphorus owing 

 to the vigour with which this element attacked tlie apparatus. 



A piece of phosphorus about the size of a pea was placed in tlie quartz 

 flask and the current passed for some time. At first the phosphorus caught 

 fire and burned until apparently all the oxygen in the flask had been used 

 up. Then on heating the flask gently the phosphorus vapourized, but 

 very soon the glass capillary tubes surrounding the electrode connexions 

 were attacked and broken, which resulted in the spark passing across between 

 the platinum connexions, not between the electrodes. Then quartz tubing 

 was used for insulating the wires, the ends being closed with plaster of 

 Paris. When the current had passed for a short time, the platinum wires 

 round the electrodes were attacked and broken. It was found that iron 

 was not affected, and so it was substituted for the platinum. But before 

 any photographs of the spectrum could be taken, some phosphorus had 

 formed a red deposit on the side of the flask, which deposit was supposed 

 to be red phosphorus. But it would not vapourize again, even when made 

 red-hot with a flame from a Meeker burner, but turned black. This deposit 

 prevented the image of the spark from being focussed on the slit of the 

 spectrograph. The phosphorus had evidently attacked the quartz, as nothing 

 would remove the black substance except hydrofluoric acid, which of course 

 removed a coating of quartz at the same time, but if cautiously used is 

 exceedingly convenient for cleaning the tube. 



This shows the extremely vigorous manner in which phosphorus attacks 

 quartz and platinum. The gold electrodes were apparently unaffected. 



The spectrum of phosphorus was eventually obtained by sparking the 

 electrodes in phosphoretted hydrogen prepared from caustic potash and 

 phosphorus. Some phosphorus was deposited on the quartz tube, but by 

 keeping one side of the tube heated all the time it remained transparent. 



The spectrum obtained showed some hydrogen lines, but only four lines 

 due to phosphorus, which consist of two pairs which are very characteristic, 

 and are situated in the extreme ultra-violet. ■ 



A most peculiar violet light was emitted when the phosphorus vapour 

 was being sparked. 



