,04 Continuation of the Experiments and Obfervations 
In favour of the exiAence of an acid in inflammable air, it 
has been Lid, that if this air be pafl'ed through water tinged 
blue by litmus, it reddens inflantly. I have feen this fre- 
quently happen when inflammable air has been exti acted horn 
iron by fpirit of vitriol; but it this air be wafhed, by palling it 
through lime-water, and then pa fled through, or agitated in, 
an infulion of litmus, it will not difcolour it in the lealt : this i 
have feen done by Mr. fontana in June 177Q. It has alio 
been laid, that inflammable air and alkaline air, mixed toge- 
ther, form a cloud ; but this has been fully difproved by Dr. 
Priestley, in the fourth volume of his Obfervations. 
That an earth of any kind is eflentially requifite to the con- 
Aitution of inflammable air, leems to me utterly improbable ; 
nor do I know of any experiment from whence it can be infer- 
red. That metallic fubflances may be held in folution by 
inflammable air is certain ; but it is equally fo, that they no 
way contribute to its inflammability*, and are quite diAinct 
•from it. 
But the opinion, that inflammable air confiAs of refpirable 
air fu per- 1 at u rated with phlogiflon, is grounded on very fpecious 
arguments drawn from experiments to be found in various 
parts of Dr. Priestley’s works, which delerve fo much the 
more attention as the fa&s mentioned by that excellent philo- 
fopher are not to be queflioned. I fhall endeavour to Aate 
them with accuracy ; but fhall at the lame time accompany 
them with fuch remarks as feem to me to invalidate the con- 
clufion that has been drawn from them. 
In the firft volume of Dr. Priestley’s Obfervations it 
appears, that a quantity of Arong inflammable air, having 
been agitated in a glafs jar immerfed in a trough of water, 
* Z J'RIESTLEX, 268. 
7 
the 
