450 Abbs fontana’s Account of Airs ■ 
II- 1 8,11+y ; from whence it appears, that the air of this 
14th of February was better than it had been for fix 
months before. There can be no doubt of the accuracy 
of the experiments, becaufe I compared the air taken at 
different times with that which I had firft ufed in the 
month of September, and which I had preferved in dry 
glafs bottles accurately flopped. Now if the formulas ex- 
prefied above are compared together, it will be found, 
that the difference between the firft terms is of twelve 
parts, and that between the latter of feven; that is, of 
one tenth and one twenty-fourth of the whole quantity 
of air: which are much greater differences than thofe 
mentioned above. Notwithftanding this, I could not 
perceive any particular change of health, or facility of 
breathing, arifing from thofe changes of the falubrity of 
the atmofpherical air; and I am informed, that no par- 
ticular difeafes appeared which could indicate any re- 
markable change of air. 
Nature is not fo partial as we commonly believe. She 
has not only giben us an air almoft equally good every 
where and at every time, but has allowed us a certain la- 
titude or a power of living and being in health in quali- 
ties of air which differ to a certain degree. By this I do not 
mean to deny the exiftence of certain kinds of noxious 
a 
air 
