Formation of nitrous Acid. 263 
means of the bent tube reprefented in fig. 3. of the above- 
mentioned Paper, whenever from the flownefs of the abforp- 
tion he thought there was too fmall a proportion of phlogifti- 
cated air in the tube. 
My reafon for this manner of proceeding was, that as my 
firft experiment feemed to fhew, that the dephlogifticated air 
ought to be in a rather greater proportion to the phlogifticated 
than the latter did, I was fomewhat uncertain as to the pro- 
per quantities, and doubted whether I could proportion them 
in fuch manner as that it fhould not be necefiary, during the 
courfe of the experiment, to add either dephlogifticated or 
common air. I therefore mixed the airs in fuch proportion, 
that I was fure there could be no occafion to add the former ; 
fince it was much eafier, as well as more unexceptionable, to 
add common air than dephlogifticated air. 
On December 24, as the air in the refervoir was almoft all 
ufed, this apparatus was again filled in the prefence of moft of 
the above-mentioned Gentlemen, with a mixture of the lame 
dephlogifticated air and common air, in the fame proportions 
as before; and the fame thing was repeated on January 19. 
On January 23, the bent tube was, by accident, railed out 
of one of the glafles of mercury into which it was inverted, 
by which it was filled with air, and a good deal of the foap-lees 
were loft ; there, however, was enough remaining for exami- 
nation. 
On January 28, and 29, the produce of this experiment 
was examined in the prefence of Sir Joseph Banks, Dr. 
Blagden, Dr. Dollfuss, Dr. Fordyce, Dr. Heberden, 
Dr. J. Hunter, Mr. Macie, and Dr. Watson. It appeared 
that 9290 mealures of the mixed air had been forced into the 
bent 
