particular form under which each acid appears.” To de- 
phlogidicated air in its date of fixity, therefore, he gives 
the title of the acidifying or oxygenous principle ; and con¬ 
cludes farther from his experiments, i. “That, when 
combined with the matter of fire, heat, and light, this 
principle produces dephlogidicated air; though he confi- 
ders this pofition as not capable of abfolute demonftration. 
It muff not, therefore, be confounded with the following ; 
which, he fays, are fupported by experiment and politive 
proofs. 2. That the fame acidifying principle, combined 
with phlogidic fubdances or charcoal, forms fixed air. 3. 
That with fulphur it forms vitriolic acid. 4. That with 
nitrous air it forms nitrous acid. 5. Thatwith Kunckel’s 
phofphorus it forms the phofphoric acid. 6. With fugar 
it forms the acid of fugar, &c. 
The opinion of M. Lavoifier has in part been adopted 
by Mr. Kirwan; whofe Treatife in 1787, informs us, 
“ that dephlogifticated air becomes an elfential condiment 
part of acids. All acids (he adds) confid of two princi¬ 
ples: one peculiar to each, which, in the opinion of the 
antiphlogillians, has not as yet been decompofed, and con- 
fequently mull: be looked upon, relatively to the prefent 
date of our knowledge, as a fim-ple fubftance: the other, 
pure air , in a concrete fiate; that is, deprived of the 
greater part of its fpecific heat, and condenfed into a fmail- 
er volume. The fird they call the acid bafis ; the lad, the 
oxygenous principle: thus the vitriolic acid, according to 
them, confids of fulphur as its bafis, and pure air in a 
concrete date as its acidifying Qr oxygenous principle. 
This doctrine has been admitted by fome of the abled de¬ 
fenders of phlogidon, and particularly by M. de Mor- 
veau, with this Angle modification, that the bafes of acids 
contain phlogidon, which they lofe on uniting to pure air: 
yet it feems very difficult to conceive how pure air can 
unite to phlogidon, a fubdance to which it has the greated 
affinity, without forming a new compound endowed with 
very different properties from thofe which it poirdfed be¬ 
fore fuch union. It feems therefore more reafonable to 
conclude, either that it forms water, as Mr. Cavendiffi 
thinks; or fixed air,” as Mr. Kirwan afterwards endea¬ 
vours to prove. 
With regard to the nitrous acid, the experiments of Mr. 
Cavendiffi, as well as of the French chemids, leave no 
room to doubt that it is produced during the deflagration 
of dephlogidicated and inflammable air. Mr. Cavendiffi 
has ffiewn, that the nitrous acid may be formed by taking 
the eleTric fpark in a mixture of three meafures of phlo- 
gidicated air, and feven of dephlogidicated air; or, in 
weight, one part of the former, and about 2*6 of the lat¬ 
ter. Mr. Kirwan is of opinion, that 100 grains of pure 
dry, and colourlefs, nitrous acid, contain 38*17 grains of 
fixed air as its acidifying principle, 57*06 of nitrous bafis, 
and 4*77 of phlogidon united to the nitrous bafis. With 
regard to the nitrous bafis itfelf, he fays that one third of 
its weight is phlogifiicated and two thirds dephlogidicated 
air, both in a concrete ftate. 
“ Nitrous bafis (fays Mr. Kirwan), faturated with phlo¬ 
gidon, conditutes nitrous air: 100 grains of this bafis 
take up nearly 22 of phlogidon. Hence the conftituent 
principles of nitrous acid are fixed air, dephlogidicated 
air, phlogifticated air, and inflammable air, all in their 
concrete date. 
“ Red, yellow, green, and blue, nitrous acids, when thofe 
colours are intenfe, owe their origin to the abforption of 
nitrous air; and confequently the proportion of their prin¬ 
ciples is variable, though all have the dephlogidicated acid 
for their ground. From Dr. Priedley’s experiments it 
appears, that nitrous vapour confids of nitrous acid uni¬ 
ted to three or four times its weight of nitrous air and a 
little water.” 
Toffiew that nitrous air is not a condiment principle of 
the nitrous acid, but that fixed air is, Mr. Kirwan ob- 
ferves, that pure nitrous acid enters without decompofi- 
tion into fixed alkalies, and forms nitre. Now if nitre be 
Vol. I. No. 5. 
diddled in a good earthen retort, it will be wholly decom¬ 
pofed; and fo alfo will the acid itfelf, except a few drops 
which pafs in the beginning of the didillation, and no¬ 
thing but dephlogidicated air, more or lefs pure, and con¬ 
fequently intermixed with phlogidicated air and a flight 
proportion of fixed air, will be found: thele, therefore, 
are its true condiment parts when dilengaged from fub- 
dances that cannot communicate phlogidon to it in any re¬ 
markable quantity, fuch as alkalies and earths; but if it 
be feparated from fubfiances that contain phlogidon, fuch 
as metals, it will then indeed be refolved into nitrous air, 
and dephlogidicated air more or lei's pure, the phlogidon 
of the fixed air being detained by the metal. Mr. Ber- 
thollet, who feems to have made the experiment with the 
greated exaftnefs, produced 714 cubic inches of dephlo 
gidicated air from a Troy ounce of nitre. This, howe¬ 
ver, was far from being of the pured kind; and Dr. 
Priedley, Mr. Berthollet, and Mr. Succow, oblerved, 
that the air which fird pafles contains fixed air, and ren¬ 
ders lime-water turbid. Here then we have three of the 
condiment parts of the nitrous acid, with fcarcely any ni¬ 
trous air; which the antiphlogidians fuppofe to be one of 
the condiment parts of the acid, and to make two-thirds 
of its bulk when exhibited in an aerial form.” 
To obviate an objection that the quantity of fixed air 
thus obtained is too fmall to deferve to be ranked among 
the condiment parts of the nitrous acid, Mr. Kirwan fird 
enquires in what proportion it ought to exid there ; and 
though this is variable, according to the different dates 
of the nitrous acid with refpedt to phlogidication, he 
reckons it at one third of the acid as exiding in tire nitre ; 
and from the decompolition of this fixed air, and the phlo¬ 
gidon emitted by it of confequence, he attributes the 
phlogidication and rednefs of the nitrous acid when ex- 
pofed to more heat. As a proof that fixed air may be de¬ 
compofed in this manner, he adduces two experiments of 
Dr. Priedley. In one of thefe, dephlogidicated air was 
obtained by means of acetous acid in that concentrated 
date in which it is called radical vinegar. Having mixed 
half an ounce of the acid with two ounces of calcined 
whiting, he obtained from it 350 ounce-meafures of air; 
of which about one-third was fixed more in the fird por¬ 
tions, and lefs in the lad. The dandard of the reliduum 
in the fird portions was i*66, in the fecond 1*42, and in 
the third 1*38 ; which is very near the goodnefs of com¬ 
mon air. The whiting then weighed 760 grains. On add¬ 
ing a quarter of an ounce more of radical vinegar, and 
repeating the operation, 120 ounce-meafures of air were 
obtained, and the whiting was reduced to 730 grains. A 
third operation, in which another quarter of an ounce of 
vinegar was added, reduced the matter to 489 grains ; but 
the lad portion of air extracted had no fixed air, and was 
confiderably better than that of the atmofphere.—The 
other experiment was made with lime-done alone ; from 
four ounces of the white cryjials of which were obtained 
830 ounce-meafures of air, the fird portion of which had 
only one-fourth of fixed air, and the dandard of the refi- 
dutim was never better than 1*56, nor worfe than 1 *66; 
fo that it was nearly of the goodnefs of common air. 
After detailing many other experirnents, he fays : 
“ Here then are feveral ways of decompofmg the nitrous 
acid ; and in one only it is refolved into nitrous and dephlo¬ 
gidicated air; and in this way it may, at lead, be ffrongl.y 
fufpected to receive an addition of another principle 
Why th'en fliould thefe be regarded as its conditupht prin¬ 
ciples ? And as in the tw o limpled methods of ddcdtftpof: 
tion, in which the re-adlion of no foreign fubdance can be 
fufpeded, it appears in the form of dephlogidicated, phlo¬ 
gidicated, and fixed, air ((he former always containing a 
portion of the tvvo laft), why then ffiould not thefe be ac¬ 
counted its true condiment parts ?—This theory is further 
confirmed by reflecting on the manner in which nitrous 
acid is generated by nature. Mr. Thouvenel found that 
this acid is conflantly produced when chalk is expofed to 
