172 Dr. Thomas Thomsons Experiments 



following table shows the composition of the air after 

 standing over the water. 



Azotic. Oxygen. 



1. Fresh extracted of . 71-48 + 28-52 



2. After one day . . 74*43 + 25-57 



3. After two days . . 75-38 + 24-62 



4. After three days . . 77-51 + 22-49 



5. After four days . . 80*97 + 19-03 



2. The 5*25 cubic inches extracted from the second 

 quantity of water by boiling was treated in the same way; 

 excepting that the 11 cubic inch jar containing the air, 

 instead of standing open on the water-trough, was corked 

 tight. The result was as follows : 



Azotic. Oxygen. 



1. Air newly extricated composed of 70-32 + 29-69 



2. After one day 72-5 + 27-5 



3. After two days 73-44 + 26-54 



4. After three days 73-35 + 27*65 



5. After four days 77-43 -h 22-57 



Here, as in the first case, the oxygen was absorbed 

 more rapidly than the azotic gas ; but the rapidity of this 

 absorption was somewhat diminished by corking the glass 

 in which the air was kept. 



IV. — Alteration produced on Common Air by leaving it 

 standing in a glass vessel inverted on the water-trough. 



Curious to know whether a similar diminution in the 

 quantity of oxygen in common air would take place when 

 left standing over the water trough, as had taken place in 

 the preceding experiments with air extricated from water 

 by boiling, I put ten cubic inches of common air, collected 

 at the window of my laboratory on a windy day, into a 

 cylindrical glass jar and left it standing inverted over the 

 water-trough, analyzing every day one cubic inch by means 

 of phosphorus, till the whole was exhausted. The follow- 

 ing table shows the result of these analyses. 



Azotic Oxygen. 



1 . After standing 24 hours . 79-47 H- 20-53 



2. After two days .... 79*27 + 20-73 



3. After three days . . . lost 



4. After four days . . . . 79*65 + 20*35 



