206 Experiments on the Production of Air 



It must be remembered that I here consider the separa- 

 tion of the air from water as a simple operation ; and that 

 I do not take into the account the purification, or rather 

 the generation, of this air. Though there is great reason 

 to conclude that these two operations are very nearly 

 connected, yet, to simplify my inquiries, I shall, in the 

 first place, consider the appearances as they presented 

 themselves to my senses. It will be easy afterwards to 

 draw any conclusions from the results of the experi- 

 ments which a careful examination and comparison of 

 the various phaenomena will justify. 



Experiment No. n. 



The globe No. 6, with human hair, furnished still less 

 air than that with ravelings of linen in the last-mentioned 

 experiment ; but notwithstanding the smallness of the 

 quantity, it was considerably superior in quality to 

 atmospheric air, for, proved with nitrous air, it gave 

 i 0_|_ 2W i.45> or 155, whereas common air proved 

 at the time gave i a -f- i n = 1.08, or 92. 



Experiment No. 11. 



To ascertain the relative goodness of the air furnished 

 by the water in these experiments, and of that produced 

 by exposing fresh healthy vegetables, in water, to the 

 action of the sun's light, according to the method of Dr. 

 Ingen-Housz, I collected a small quantity of air from a 

 stem of a pea-plant, which had four healthy leaves upon 

 it, exposed in water to the sun's light, and found it to 

 be much inferior to that furnished in the experiments 

 with silk and the various other substances I made use of. 

 Proved with nitrous air, it gave i a -\- 2 n= 1.05, or 195. 



An entire plant of housewort, of a moderate size, ex- 



