on the Absorption of Air hy Water, 175 



VI. — Alteration produced in Air hy standing ovefi' distilled 



and newly boiled Water. 

 We have seen that when air is left for 25 days over 

 common river water it undergoes no sensible alteration in 

 its composition. But the case is very different when air is 

 left in contact with newly boiled distilled water. I analyzed 

 the residual air in the ten trials exhibited in the last section 

 by leaving it in each case for 24 hours over the water-trough 

 with a stick of phosphorus in contact with it. The dimi- 

 nution of volume was considered as the bulk of oxygen 

 which it contained. The proper corrections being made 

 for alterations in the barometer and thermometer which 

 had taken place during the interval, the following table 

 exhibits the volume of azotic and oxygen gases contained 

 in these residues : 



Vol. of Oxygen. Vol. of Azotic gas. 



1st 10-16 76-93 



2nd 16-72 73-90 



3rd 7-71 64-36 



4th 6-22 80-37 



5th 11 -51 75-22 



6th 13-44 72-22 



7th 13-37 67-32 



8th 13-42 68-36 



9th 10-48 69-42 



10th 4-59 72-13 



But, in order to be able to judge more accurately of the 

 constitution of this residue, we shall suppose it to amount 

 in each case to 100 volumes, and set down the number of 

 volumes of oxygen and azotic gas of which it is composed : 



Vol. of Oxygen. Vol. of Azotic gas. 



1st 11-67 88-33 



2nd. .... 17-35 82-65 



3rd 10-70 89-30 



4th 7-18 92-82 



5th 13-27 86-73 



6th 15-70 84-30 



7th 16-57 83-43 



8th 16-41 83-59 



9th 13-12 86-88 



10th. . . . • 5-99 94-01 



Mean 12-80 87-20 



