54 
will be a little ball of yellow fulphur 
fwimming on the middle of the hquor, 
and a good deal of fulphur will be found 
atthe bottom of it by the cryftals on the 
fides continually fliding down into the 
diguor as others are formed. 
Sulpbur is prcduced in the very fame 
manner, by means of water impregnated 
with hepatic air. “Phe only difference is, 
that the fame dancing vapour is not feen 
in this procefs as in that of vitriolic acid 
air, which is @ curicus circumftance in 
the experiment. In the courfe of thefe ex- 
periments, Dr. P. found that a good pyro- 
phorus might be made of fulphur and 
iton only. He found alfo, that quick- 
lime; when expofed to the air, gets 
weight in the proportion of between 320 
and 300 grains to an ouncé, after'which 
it will imbibe no more. 
The fecend paper contains * Experi- 
ments relating to the change cf place in 
different kindsof air through feveral in- 
terpofing fubftances.”” Dr. Prieftley ob- 
ferves, that one of the moft extraordinary 
circumftances that ever occurred in the 
courfe of his experiments, was that of 
the vapour of water, or of mercury, 
changing places with any kind of air, in 
veffels, which, for moft purpoles might be 
confidered as air-tight. He had Jong fince 
obferved, that different kinds of air, ca- 
pable of forming a chemical union, would 
do it through a bladder that was perfeétly 
air-tight, and that in this manner pure 
air was imbibed by the blood through 
the membrane of the lungs, while the 
phlogifton (azote) was tran{mitted into 
the air within them. It is now found, that 
what was done by air and water, will be 
done by any two kinds of air, whether 
they have any affinity to one-another’ or 
not. ‘* Having,’? fays Dr. Prieftley, 
«« procured earthen veffels of a very clofe 
texture, fo asto be apparently impervious 
te air, I could fill them with any particu- 
lar kind of air, and then place them, in- 
verted, ina large glals jar, containing a 
different kind ef air; I then heated the 
{mail earthen vefiels through the giafs 
jar, by means of a burning lens, and 
never failed to find, after the experiment, 
that the air within the earthen veflel was 
the fame with that which had been on 
the outfide of it, while rhat within it 
was mixed with that on the outfide. In 
fome cafes, the mixture was a chemical 
ene;- inothers, the two airs were only 
diffufed through one anctber.’” The ex- 
periments in tbis paper.are curious, and 
detailed at large. 
The third paper confifts of a courfe of 
Proceedings of Learned Societies. 
[March 1, 
‘© Experiments relating to the Abforption 
of Air -by Water.’? In the fourth, are 
feveral ‘*-Mifcellaneous Experiments re- 
lating to the Doétrine of Phiogiften.” 
From the fifth, which gives an account of 
experiments on the production of air by 
the freezing of water; Dr. Prieftley ob- 
ferves, that ‘* the moft natural inference 
is, that water, when reduced by any 
means to the flate of wapour, is, in part, 
converted into phlogifticated air; end, 
that this is one of the methods provided 
by nature for keeping up the equilibrium 
of this conftituent part of the atmo- 
{phere : as the influence of hght on 
growing vegetables is the means of 
recruiting that other, part of i, and 
both of them are fubjeét to av- 
forption and diminution in feveral na- 
tural procefles. Inflammable air fF 
have alfo fhewn to be cenvertible inte 
phlogiftigated air; and this is another 
means of fupplying the atmofphere with 
this ingredient in its compofition.”” 
The /xth, and laf&{ of Dr. Prieftley’s 
papers, contains ‘* Experiments on Air 
expefed to heat in Metallic Tubes.”’ 
One remarkable circumflance attending 
the heating of air in earthen tubes, and 
alfo in thoie of metal, is, that no mixture of 
dephlogifticated and inflammable air will 
explode in them, though it always does 
in tubes of glafs, in which there is no 
metallic ingredient: but, in tubes of flint- 
glafs, in which there is the calx of lead, no- 
explofion will take place ; in theattempt, 
they become black, as they do when in- 
flammable air only is heated in them, 
this air muft be feparated from the de; h- 
logifticated, and unite with the calx of: 
lead. It is therefore probable, that the 
fame happens in the metallic tubes, 
though the metal is not ina ftate of celx, 
but may be. fuperfatured with phlogifton, 
Dr. Prieftley alfo found, that when he 
threw the focus of a burning lens upon: 
fome clean filings of copper in inflamma- 
ble air, much of the air difappeared, 
having, no doubt, been imbibed by the 
metal. For thefe experiments, the mix- 
ture confifted of one part of vital, and 
two parts of inflammable air, each very 
pure, fuch as made the loudelit expiofions 
when a lighted candle was prefented to 
any portion of it ; but neither in tubes of 
iron, copper, filver, or gold, was there 
any explofion, though as flrong a heat as 
they would bear without melting, was” 
continued a confiderable time. ‘The re- ~ 
mainder of this paper is devoted to 
‘© Experiments of the tran{miffion of © 
Air through the fubftance of fome Me- — 
a5 tallic 
