1877.] Dr. R,. A. Smith on the Examination of Air. 515 



These results are very irregular. It was thought that the solution of 

 barium hydrate used was rather weak. With a much stronger solution 

 the following experiments were made. 



Aspiration. 



Volumes C0 2 per million volumes air. 



Experiment 5. 

 1st bottle gave 80 



2nd „ 02 



3rd , 62 



4th „ 53 



5th „ 18 



6th „ 45 



Total 320 in series of 6 bottles. 



Experiment 6. 



1st bottle gave .. 



115 



2nd 



... 71 



3rd 



66 



4th 



. 62 



5th 



62 



6th 



. 63 



320 is low for Manchester ; 438 is pro- 



bably correct for the spot tried. Total 438 in series of 6 bottles. 



It is clear from these experiments that a series of three washing- 

 bottles containing barium hydrate are not sufficient to absorb the 

 carbonic acid from the air aspirated through them ; with a series of six 

 bottles it is troublesome to work, but more, and perhaps all, is obtained. 

 Equal speeds are compared here and equal solutions. With the three 

 absorbents the strong baryta solution gave still too little. 



Sulphuric Acid (Sulphates) in the air. 



Devonshire Street, Manchester, 

 1876. 



By shaking. 



, Aspiration with 

 j 3 wash-bottles. 



Grammes 

 per million 

 cub. metres. 



Grains 

 per million 

 cub. feet. 



I Grammes 

 per million 

 cub. metres. 



Grains 

 per million 

 cub. feet. 



Yard : Nov. 10, clear afternoon . . . 

 „ „ 11, fine, frosty morning 

 „ 13, raining ; sheltered 



3482 

 4352 



4352 

 4352 

 2611 

 3482 



1521 

 1902 



1902 

 1902 

 1141 

 1521 



4612 

 1731 



3458 

 4612 

 2017 

 3991 



2015 

 756 



1511 

 2011 

 881 

 1744 





3772 



1648 



3253 



1486 



