[325]. It is known in commerce by this name, since it is prepared on a large scale, by distilling sugar with nitric acid. It derives the term oxalic acid, from the plant which so abundantly contains it, viz. oxalis acetosella, or wood sorrel.
[326]. Essential Salt of Lemons. “The preparation sold under this name, for the purpose of removing iron moulds from linen, consists of cream of tartar, and super-oxalate of potass, or salt of sorrel, in equal proportions.” Pharmacologia.
[327]. The parents of this child suppose that the violence of the screaming ruptured the vesicles by which the breathing was impeded, and thus proved an unexpected means of cure.
[328]. See “An account of the case of a man who died of the effects of the fire at Eddystone Light-house,” by Mr. Edward Spry, Surgeon, at Plymouth. Phil. Trans. vol. xlix, part 2, p. 477, A. D. 1756.
[329]. There are some exceptions to this law; for instance, the tincture of litmus, and litmus paper, are always rendered more intensely blue, by the addition of alkalies. There are also other bodies, besides alkalies, which change the yellow colour of turmeric to a brown. Upon this subject see an interesting paper in the 26th number of the Journal of Science and the Arts, p. 315, by Mr. Faraday, entitled “On the changing of vegetable colours as an alkaline property, and on some bodies possessing it.” By this communication we are informed that even the strong acids redden turmeric paper, and that a very weak nitric acid gives it a tint exactly like that produced by an alkali. Different metallic salts are characterised by similar effects.
[330]. A new alkali has been lately discovered in a mineral called Petalite, by M. Arfwedson, a young Sweedish chemist, but as the extreme rarity of the substance will prevent its ever becoming an object of forensic interest, we shall pass it over without further notice. Some new alkaline principles have also been developed by the French and German chemists, in the analysis of certain vegetables, but as these bodies have a physiological action, which is wholly independent of their alkalinity, they will be more properly noticed under the history of the vegetables which contain them.
[331]. Should the solution contain a small portion of lime, as may occasionly happen, the cloud will be very slight, and cannot give origin to any important fallacy.
[332]. Orfila, vol. i, p. 404.
[333]. Essay on Poisons, page 143.
[334]. Orfila, Lib. Cit.