Formation of nitrous Acid. 2~i 
nitre produced more or lefs phlogifticated. Now, in this expe- 
riment, the bulk of the phlogildicated air was i2 T a - that of 
t lie foap-lees. I11 my firft experiment it was 1 i-fL, and in my 
laft 1 o .i 8 _ 0 - . 
As many perfons feem to have fuppofed that the diminution 
of the air in thefe experiments is much quicker than it really 
is, though I do not know any thing in my Paper which fhould 
lead to luppoie that it was not very flow, it may be proper to 
fay fomething on this head. As the quicknefs of the diminu- 
tion depends fo much on the power of the eleflrical machine,. 
I can only fpeak as to what happens with the machine ufed in 
thefe experiments. This was one of Mr. Nairne’s patent 
machines, the cylinder of which is 12I inches long, and 7 
in diameter. A conductor of <; feet long, and 6 inches in 
diameter, was adapted to it, and the ball which received the 
fpark was placed at two or three inches from another ball, 
fixed to the end of the conductor-. Now, when the machine 
worked well, Mr. Gilpin fuppofes he got about two or three 
hundred fparks a minute, and the diminution of the air during 
the half hour which he continued working at a time, varied 
in general from 40 to 120 meafures, but was ufually greateft 
when there was moft air in the tube, provided the quantity 
was not fo great as to prevent the fpark from pafling readily. 
The only perfons 1 know of, who have endeavoured to re- 
peat this experiment, . are, M. Van Marum, afliffed by M. 
Paets Van Trootswyk; M. Lavoisier, in conjunction 
with M. Hassenfratz ; and M. Monge. I am not acquainted 
with the method which the three latter Gentlemen employed, 
and am at a joi's to conceive what could prevent fuch able phi- 
lolophers from iucceeding, except want of patience. But M. 
Van Marum, in his Premiere Continuation des Experiences 3 
faites 
