366 Dr. ingenhousz on the Salubrity 
was this : I had made ufe of fea water for the experiment 
on the 3d of November, whereas I had made ufe of pump 
water in examining the fea air kept in bottles at Oftend. 
I thought I had no right to draw any conclufion from the 
fa£t till I was convinced that the making this experiment 
in common or in fea water would make no difference in 
the re fult. This confideration made me flay one day 
longer at Oftend, on purpofe to fatisfy my mind on this 
head, left I fhould never find another opportunity of 
doing it. I immediately ordered a pail full of fea water 
to be brought to my lodging, and made feveral compara- 
tive trials with atmofpheric air in common water and in 
this fea water; but I could not obferve any real difference 
in the refult. Thus all degree of fufpicion about the dif- 
ference of the refult from this caufe was now at an end 5 . 
There now only remained fome little fufpicion that 
the air gathered on the fea, and kept in phials, might- 
have undergone fome alteration ; this might have been the 
cafe, as I had found in fome former experiments made 
in England, that air kept in bottles was fometimes 
liable to alterations, which I think is partly to be 
afcribed to the difficulty of finding bottles fo well fecured 
by a ground ftopper as to fhut out every communication 
with the external air, and partly, perhaps, to the na- 
ture of air, which is not in itfelf an unalterable fubftance, 
as 
