31 
Hitherto we have had the composition of the air given in 
numbers varying a tenth per cent — specimens have generally 
been taken from rooms on streets or open places indiscrimi- 
nately. It is the author’s wish to show that variations are 
dependent on the conditions of soil, situation, wind, &c., and 
that the oxygen and carbonic acid together may with very 
minute analysis guide us in our sanitary inquiries. The 
paper cannot easily be given in abstract, further than by 
adding a table of the analyses showing the average numbers 
obtained in various places : — 
Analyses of Atmospheres varying in Oxygen. 
.Oxygen per 
cent. 
Avge. Nos. 
N.E. sea shore and open heath (Scotland) 20 '9 9 9 
Tops of hills (Scotland) 20-98 
In a suburb of Manchester in wet weather 20 - 98 
Ditto ditto ditto 20-96 
Front of street fths of mile from Exchange, Manchester... 20-945 
At the back part of the house 20 ’9 3 6 
Low parts of Perth 20-935 
Swampy places (favourable weather) 20-922 to 20 - 95 
In fog and frost in Manchester 20 - 91 
In sitting room which felt close, but not excessively so... 20'89 
In a small room with petroleum lamp, well ventilated ... 20-84 
Ditto after six hours 20-83 
Pit of Theatre, 11 30 p.m 20-74 
Gallery, 10 30 p.m 20-36 
In large cavities in mines 20-77 
In currents 20-65 
Under shafts 20-424 
In sumps 20T4 
When candles go out about 18-5 
The worst specimen yet examined in the mine 18*27 
Very difficult to remain in for many minutes 17-2 
