193 
most convenient. It must be observed that the amount 
rises exactly where you might expect more organic matter 
to exist. The lowest is from Prince’s-road, outside the town 
and almost a half a mile from the extreme of the 
Manchester houses. The next is obtained from an empty 
yard behind my laboratory, but it is still pure because there 
was wind and rain, and any one who observes how unusually 
pleasant it is to breathe the air even of a smoky town during 
rain and wind will not be suprised. I have not yet, however, 
had the purest air. I shall require to make a campaign on 
the moors, hills, and seas before I can give numbers for this. 
I have not even obtained the best given on land at a distance 
from manufactures. Ah this will be done in time * 
In my office the amount is larger than outside, but the air 
is not so bad as it is in front and not so good as sometimes in 
the front where it is open. From the back of the laboratory 
during fog the ammonia was much higher, but during one 
day it was excessive, and a special examination of it was 
made in several streets. The highest amount was obtained 
at the front of the Cathedral, about mid-day, on the 8th of 
February, 1878, when the amount was 1'25, or 11J times 
more than it had been found in Prince’s-road, showing a 
considerable range. 
Mgms. of Ammonia 
per cubic metre 
of air. 
Prince’ s-road *086 
Open yard during rain *119 and ‘102 
Front of laboratory *167 ordinary. 
Office -167 
Front and back during fog *476 
Close shut-up room *413 
Closet outside *800 to f 900 
Densest part of fog ....1’25 
* Since the paper was read I examined trees and stones at Skelmorlie and 
Wemyss Bay, finding very little ammonia. 
