Still, he made some observations on the analysis of air, and continued his inquiries on the generation of air from water.
As the duties of his office left him ample opportunity to turn the active powers of his mind to account, he again attempted to establish a school, and this time with a success far beyond his anticipations.
The dexterous Mr Kirwan, not long before he himself embraced the French doctrine, furnished Priestley with 223 an argument which satisfied him that this cardinal fact can be accounted for without excluding phlogiston. Since therefore the supposition is exceedingly convenient, if not absolutely necessary, to the explanation of many other facts in chemistry, it is at least advisable not to abandon it.鈥�
Air of the former kind, besides having been discovered in various caverns, particularly the Grotta del Cane in Italy, had also been observed on the surface of fermenting liquors, and had been called gas (which is the same with geist, or spirit) by Van Helmont and other German chemists; but afterwards it obtained the name of fixed air, especially after it had been discovered by Dr Black of Edinburgh to exist, in a fixed state, in alkaline salts, chalk, and other calcareous substances.鈥�
In this manner I found that air is produced in great plenty; but, upon examining it, I found to my great surprise that little more than one half of it was fixed air, capable of being absorbed by water; and that the rest was inflammable, sometimes very weakly, but sometimes pretty highly so.鈥�