16 



DR. R. ANGUS SMITH ON THE 



like all other investigations^ after leading us onward one 

 stepj it shows us that there is another to take. 



If emanations arise from foul places^ they must occupy 

 space. They are mixed gases and vapours. When we use 

 caustic soda to absorb the carbonic acid^ perhaps we absorb 

 some vapours also, and indeed I always find that in a eudio- 

 meter we are apt to obtain too much carbonic acid in cases 

 where the quantity is small, unless extreme care is used. 



Street and Suburb Air, Manchester, compared with Closet 

 or Midden Air. 



Time. 



Air from closet or midden 



Air from front door of 



behind laboratory. 



Laboratory. 



1863. 



Oxygen, vols, per cent. 



Oxygen, vols, per cent. 



Dec. I. 



2o-8o 



20-90 



„ 10. 



20'85 



20-96 



„ II. 



2079 



20-98 



» n 



20*72 



20-90 



„ 15- 



20*87 



20-90 



» >• 



20*76 



20-02 



,> 17- 



20-59 



20-96 



>i >< 



20-85 



20-78 



» » 



20-90 



20-83 



„ i8. 



20-21 



20-91 



,, » 



20-58 



20-92 



» » 



20-74 



20-87 



» » 



20-40 



21-02 



), ), 



20-77 



21-00 



„ 19- 



20-99 



20-83 



» » 



20-70 



20-98 



j> >j 



20-82 



20-88 





20-46 



21-01 

 20-87 



,, 21. 



20-56 



20-92 



II I) 



20-79 



2I-02 



I) 11 



20-64 



20-88 



>i )> 



20-94 



20-91 



,, „ 



20-67 



21-01 



„ 22. 



20-53 



2096 



1) >i 



20-71 



20-92 



1864. 







Feb. 26. 



20'66 



21-01 



„ 24. 



... 



21-05 



» 20. 



... 



20-98 

 20-99 

 2I-OI 

 20-94 



Average 20-70 



20-943 



Compare also the specimens from the city of Perth, p. 24. 



