This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Acetosa, Lapathum acetosum, Rumex. Sorrel or Sour-dock: a species of dock with acid leaves.
I. Acetosa Pratensis Ph. Lond. Acetosa, Pharm. Edinb. Acetosa pratensis C. B. Rumex acetosa Linn. Common Sorrel; with the leaves shaped like an arrow-head, and very short or no ears at the bottoms.
2. Acetosa arvensis, minor: Acetosa ar-vensis lanceolata C. B. Rumex Acetosella Linn. Sheeps Sorrel; with arrow-headed leaves, of which those on the stalk have no ears, those from the root long diverging ones.
3. Acetosa rotunda, P. Parif. Acetosa hortensis rotundifolia C. B. Rumex scutatus Linn. Garden or French Sorrel; with roundish leaves and ears.
The leaves of these plants are mildly acid, without any smell or particular flavour: the common sorrel is the least, the garden fort the most agreeable. They were all formerly directed as officinals; and occasionally made use of, for abating heat, quenching thirst, and preventing or correcting a tendency to putrefaction, in febrile and scorbutic disorders; but at present are less regarded, other vegetable acids having in good measure supplied their place.
The leaves yield, upon expression, a large proportion of thick, turbid, green-coloured juice: which, on standing till the feces have subsided, becomes clear and reddish, and in taste more gratefully acid than the herbs in substance. This is one of the most elegant preparations of sorrel for medicinal use, and may be advantageously joined, in scorbutic cases, to the juices of the acrid herbs: the inhabitants of Greenland, who are very subject to these distempers, are said to employ, with good succefs, a mixture of sorrel and cochlearia (a).
Greatest part of the acid matter of sorrel may be obtained also in the form of a concrete salt; by infpiffating the depurated juice to a due consistence, and setting it to crystallize. This salt is suppofed to approach to the nature of tartar: from which, however, it obviously differs, in being more acid, more easily dissoluble in water (b), and much less, if at all, purgative.
The roots of the sorrels have a roughish bitterifh taste, without any acidity. They have been looked upon as aperient and diuretic; and, in these intentions, have been sometimes made ingredients in watery infusions and decoctions, to which they communicate a reddish hue: the garden sorrel gives the lightest, the common wild sort the deepest red. It is ob-servable, that acid liquors, which in general heighten vegetable reds, destroy this red tincture of sorrel roots: alkalies change it to a purplish; chalybeate solutions, to a deep green.
The seeds of sorrel are very slightly, if at all, astringent, without acidity or bitterness. They had long a place in the shops, as ingredients in some of the old alexeterial compositions, from which they are now deservedly expunged.
(a) Bartholinus, Aft. Hoffnienf. 1671. obf. 9. (b) Neumann, Chemical Works, p. 257, 424.