792 Experiments 



A. High Pressures with Air of Low Oxygen Content. 



Experiment CCCLXXII. July 13. Sowings of barley on wet paper. 



A. Receiver at normal pressure, well corked. 



B. Similar; taken to 4 atmospheres, 3 of which are of air with 

 very high nitrogen content. 



July 14. Raised to only 2 atmospheres. Renewal has been made 

 and is made every day with air of very high nitrogen content. 



July 16. 3 atmospheres. Nothing in either A or B. 



July 17. A little germination in both. 



July 19. A. Sprouts a little stronger than those in B. 



July 22. Same. 



The air in B. contains 1.7% of carbonic acid and 11.9% of oxygen. 

 The oxygen tension at the end was therefore 13.6 x 3 = 40.8. 



Experiment CCCLXXIH. November 4. Barley and cress on wet 

 paper. 



A. Glass receiver at normal pressure. 



B. Cylindrical apparatus, at 8 atmospheres of air with low oxygen 

 content; the mixture contains 5.7% of oxygen, the tension of which 

 5.7 x 8 = 45.6 corresponds to about 2 atmospheres of air. 



November 7. A, a few seeds have germinated. 



November 8. A, a few more; B, nothing. The apparatus leaks, the 

 pressure has fallen to 6 atmospheres; it is raised to 8 with the same air. 



November 9. A few barley seeds are germinating in B; in A, the 

 sprouts are already fine. 



November 11. Same condition; decompression is made, and the 

 seeds from B are sowed on wet earth. The gas in the apparatus con- 

 tains CO, 3.2; O, 1.6; the CO tension is therefore 3.2 x 8 = 25.6. 



November 20. The cress is 3 cm., the barley 5 or 6. 



Experiment CCCLXXIV. August 2. Sowings of barley and cress. 



A. Cylindrical apparatus taken to 10 atmospheres of an air which 

 contains 9.8% of oxygen; the tension of this gas is therefore 98, cor- 

 responding to about 5 atmospheres of air. 



B. Test glass, normal pressure. 



August 3. I bring A down to 7 atmospheres; the oxygen tension 

 is only 7 x 9.8 = 68.6, or a little more than 3 atmospheres of air. 



August 4. The cress and barley have sprouted in both, but A is 

 evidently more delayed than B. 



It is already plain from these experiments that the oxygen is 

 to blame. In fact, in Experiment CCCLXXII, if we had used ordi- 

 nary air, germination would have been considerably delayed, 

 whereas it was hardly delayed at all; in the other two experiments, 

 it would have been completely stopped by pressures of 8 and 10 

 atmospheres, whereas there was only a delay explainable by the 

 oxygen tension, which was already equivalent to 2 atmospheres 

 (Exp. CCCLXXIH) or 3 atmospheres (Exp. CCCLXXIV) . 



In Experiment CCCLXXIH a new element, the high tension of 



