Physics. — ''Contribution to the knowledge of the removal of rest- 

 gases, especially for the electric vacuum ylow-lamp" By Dr. 

 L. Hamburger. (Communicated by Prof. Böf.skken). 



i Communicated in the meeting of November 30, 1918). 



§ 1. Remarks on the action of phosphorus in the gloic-lamp. 



The account of the investigations made in the end of 191G that are 

 discussed in this paper was aheady finisiied June 11 1917. Tlie autlior postponed 

 however the pubhcation until the experiments together with Mrs Holst. Lely 

 and OosTERHUis (communicated in these proceedings) had been finished. 



1894 already the Italian Malignani indicated a "chemical" method 

 technically extremely useful, to improve llie vacuum of glow-lamps: 

 viz. phosphorus.^) During the burning- of the glow-lamp, gases may 

 be liberated by several circumstances, especially in the beginning. 

 When a little phosphorus vapour is present, these liberated gases 

 will form with it under the influence of the occurring electric discharges 

 non-volatile compounds which are precipitated on the bulb wall. 

 (Comp. Ij. Houllevigue)'). As for this purpose quantities of 0,05 mg. 

 are already more, than sufiicient this precipitate is not visible, while 

 still the vacuum of the lamp has been much improved. 



The action of the phosphorus in the glow-lamp is not very simple. 

 The intricateness of the character of the phenomenon is still increased 

 by the way in which the element is introduced into the lamp. 

 Usually the filament-support of the glow-lamp is immersed in a very 

 fine suspension of phosphorus in alcohol. When it is sealed into the 

 glass bulb the filament and part of the supports are therefore 

 already covered with the red phosphorus. During the sealing- in 

 process hot air circulates through the bulb, so that it becomes very 

 hot. This is accompanied by a partial oxydation. We must therefore 

 also consider an eventual action of PjO^. But even, when this action 

 is left out of consideration, as will be done in this paper, still the 

 phosphorus is the cause of several peculiar reactions, which are 

 especially connected with the above mentioned electric discharges, 



1) Malignant D. R. P. 82076 (1894). Substances as As. S. J. have also been 

 advised, without being hardly ever used however. 



') L. HouLLEViGUE, Journ. de phys. (5) 5, 525 (1912). 



