166 



passed through an alkaline pyrogallol solution, as described 

 by W e y 1 and G o 1 1 ^). They found that most oxygen was 

 absorbed when 0.25 gram pyrogallol was dissolved in 

 10 ce. NaOH of spécifie gravity 1.03. In the nitrogen 

 purified in this way the seedlings showed however very 

 clear signs of poisoning. The apices became strikingly 

 brown and ail sorts of curvatures appeared. Since CO is 

 formed by the passage of oxygen through pyrogallol, it 

 is to this that the poisoning may be attributed. That this 

 was indeed so, became évident when the gas was passed 

 through the tube of a combustion furnace, in which there 

 was a small quantity of CuO, as well as reduced copper 

 which served to flx any oxygen which might hâve escaped 

 absorption. This CuO oxidized the CO to COg. Gas 

 treated by this method no longer gave the shghtest 

 indications of poisoning. 



The dark room. 



The dark room in which I performed the flrst part of 

 my experiments, was situated in the centre of the Botanical 

 Laboratory. In this room there was an air-shaft, by means 

 of which, fresh outside air could always be sucked through 

 the thermostat, in those experiments, in which this was 

 necessary. Afterwards in conséquence of structural changes 

 in the laboratory, this room was no longer at my disposai 

 and I continued the experiments in a small separate buil- 

 ding in the Garden consisting of two small rooms, which 

 had each a separate door to the garden. One of thèse 

 was made into a dark room in which, by a very simple 

 arrangement the outside air could be directly sucked 



^) Th. Weyl and A. Gott. Ueber die Absorption von Sauerstoff 

 durch Pyrogallol und Phloroglucin in alkalischer Lôsung. Berichte der 

 Deut. Chem. Gesellsch. 1881, 14e Jahrg.. II. 



