o aerial acid, and the former into vitiated air (Sec.Sec. 29,
89, 90). It is not so easy to furnish the reason for this, yet I will
risk it. It is known that the acids lose those properties by which they
reveal themselves as acids, by the addition of the inflammable
substance, as sulphur, the elastic acid of nitre, regulus of arsenic,
sugar, and the like, plainly shew. I am inclined to believe that
fire-air consists of a subtle acid substance united with phlogiston, and
it is probable that all acids derive their origin from fire-air. Now, if
this air penetrates into plants, these must attract the phlogiston, and
consequently the acid, which manifests itself as aerial acid, must be
produced. This they again give up. The objection that so great a
quantity of aerial acid is nevertheless obtained in the destruction of
plants, and that, consequently, these must attract the aerial acid, has
no weight, since otherwise the air in my vessels in which the peas were
contained must have become for the most part lost, which, however, did
not take place.... If plants abstract the phlogiston from the air, the
aerial acid must be lighter. But experiment shows me the opposite; I
found it, after careful weighing, somewhat heavier, but this is not
contrary to my opinion; as it is known that all acids retain water
strongly, the aerial acid must possess the same property, and this may
consequently cause the most of the weight. If all this is accurate,
another question then arises: Why do not blood and the lungs likewise
convert fire-air into such an aerial acid? I take the liberty here also
of giving my opinion of this, for how would all these laboriously
executed experiments help me if I had not the hope of coming by means
of them nearer to my ultimate object, the truth? Phlogiston, which makes
most substances with which it unites liquid as well as mobile and
elastic, must have the same effect upon blood. The globules of blood
must attract it from the air through the small pores of the lungs. By
this union they become separated from one another, and are consequently
made more liquid. They then appear bright red (Sec. 89). They must,
however, give this attracted phlogiston up again during the circulation,
and in consequence, be placed in a condition to absorb the inflammable
substance anew from the air at that place where they are in the most
intimate contact with it, that is, in the lungs. Where this phlogiston
has gone to during the circula