46 DR. R. ANGUS SMITH ON THE 



The following summary may be made of the Manchester 

 results : — 



Average of Car- 

 bonic acid per cent. 



In Manchester streets in usual weather 0*0403 



During fogs 0*0679 



About middens, of which there are thousands 0*0774 



Average of all the town specimens 0*0442 



Fogs excepted 0*0424 



Fogs and middens excepted 0*0403 



\\'Tierethe fields begin 0*0369 



In close buildings ; ,. 0*1604 



Minimum of suburbs 0*0291 



When approaching the country the amount seems occa- 

 sionally very low ; probably the lower grounds, with much 

 vegetation, are subject to variations below and above the 

 standard, and such as are not found in exposed or bare 

 regions. 



There may be noticed in Manchester a tendency towards 

 increase of carbonic acid as the day advances, as if at times 

 the ventilation could not keep down the increase of acid : 

 this is contrary to the results in a country place. There 

 is less after rain, and less during high winds. 



Carbonic Acid on the River Thames, April 1864. 



Locality. 



Wind. 



ist deter. 



London Bridge : — 



City side 



S.W. 



Carbonic 



acid per 



cent. 



■0354 

 •0383 

 •0383 



•0313 



■0344 

 •0298 

 ■0329 



•0329 



Middle 





Westminster Bridge : — 



City side 



Middle 





Before the Houses of Parliament.. 

 Lambeth Bridge : — 



Mean of 10 experiments ... 





■0343 



