[321]. Mouldiness is a peculiar plant, propagated by seeds, infinitely small; Reaumur found the interior of an addled egg mouldy, hence the seeds must have passed through the pores of the shell! Dr. Macculloch has lately announced the curious fact, that the propagation of mouldiness may be prevented by the presence of aromatic substances. See p. 177, Note.
[322]. This fact has enabled the Chemist to prepare an indelible ink, not affected by acids.
[323]. Keyser’s Antivenereal Pills consist of this mercurial salt, triturated with Manna.
[324]. Vinegar quenches the thirst, and is particularly refreshing after much bodily exertion. It was this property that invigorated the soldiers of Hannibal in their progress over the Alps; it is absurd to imagine that Livy meant to assert that the rocks were dissolved by Vinegar: the expression is only metaphorical. See Sodæ Murias.
[325]. The varieties of vinegar known in commerce, are three, viz. Wine Vinegar, Malt Vinegar, and Sugar Vinegar; to which may now be added that from wood, and which is described under the title of Acidum Aceticum Fortius, or Acidum Aceticum, e ligno destillatum.
[326]. I apprehend that the superior power of animal charcoal, over that of vegetable origin, in removing colouring matter, depends upon the peculiar texture of the former. At the same time it must be acknowledged, that there are certain phenomena which would appear to indicate the existence of a chemical difference in these substances; thus if Lime water be boiled with animal charcoal, the whole of the lime will be abstracted from the water, whereas the same effect is not produced by the action of charcoal of vegetable origin. See Liquor Calcis.
[327]. The Sulphuric acid is added for the purpose of preserving the vinegar from decomposition.
[328]. This quantity includes the alkali necessary to saturate the Sulphuric acid which is allowed to be added. 145 grains of alkali is the standard fixed by act of Parliament, which will be found to coincide with the atomic weights of these bodies.
[329]. By real Acetic acid is meant such an acid as occurs in a dry acetate; it cannot exist uncombined with water, or a base.
[330]. This is a very ancient preparation, thus Ausonius,