

442 Mr. Warr’s Thousbts on the doe Rivviene™ 
“a fmaller quantity than what might reafonably be. fuppofed a 
be loft in the procefs by the extreme volatility ef the nitrous” 
air, In order to afcertain the exa& point of faturation, flips 
of paper, flained by the juice of the petals of the fearlet fofe, ‘ 
were employed, which were the niceft teft I could procure, © 
as litmus will not thew the point of faturation of any liquor 
containing much phlogifticated nitrous acid, or even fixed ‘ 
air, but wail turn red, and fhew it to be acid, when the teft of 
thofe leaves, violets, and fome other of the like kind, will turn — 
green in the fame liquor, and fhew it to be alkaline. But the 
exact point of {aturation of fo dilute a liquor is fo very difficult — 
to afcertain, than an error might eafily be committed, not- | 
withitanding the attention beftowed upon it. Suppofing this’ 
experiment to be unexceptionable, the conclufions which may 
be drawn from it are very favourable to the hypothefis I endea- 
vour to fupport. Thirty-fix ounce meafures of dephlogifiicated 
air were obtained, and only five grains of a weak nitrous acid 
were loft in the procefi. Two hundred and eighteen grains of 
mercury out of two hundred and forty were revived, and all the 
dephlogiflicated nitrous acid employed is found to be highly phlogifti= 
cated mm the proce/s. It appears, that the nitrous acid does mot 
enter into the compofition of dephlogiflicated air; 1¢ feems only to 
Serve to abford phlogifion from the watery part of tbe mercurial: 
nitre. ¢ 
11. As this laft procefs proved very tedious and complicated 
on account of the necefflity of afcertaining the quantity of acid” 
im the receiving water, by means of an alkali which afforded a 
double fource of error in the point of faturation, I refolved to’ 
try the diftillation of dephlogifticated air from cubic nitre im a 
glafs veffel, and to draw from it only fuch a quantity of air as 
it would yield without a@ing much upon the retort, which 
latter 




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