Lastly, the Watercress has for many years held credit with the common people for curing scurvy and its allied ailments; while its juices have been further esteemed as of especial use in arresting tubercular consumption of the lungs; and yet it has remained for recent analysis to show that the Watercress is chemically rich in "antiscorbutic salts," which tend to destroy the germs of tubercular disease, and which strike at the root of scurvy generally. These salts and remedial principles are "sulphur," "iodine," "potash," "phosphatic earths," and a particular volatile essential oil known as "sulphocyanide of allyl," which is almost identical with the essential oil of White Mustard. Moreover, many of the chief Herbal Simples indigenous to Great Britain are further entitled for a still stronger reason to the fullest confidence of both doctor [5] and patient. It has been found that when taken experimentally in varying quantities by healthy provers, many single medicines will produce symptoms precisely according with those of definite recognized maladies; and the same herbs, if administered curatively, in doses sufficiently small to avoid producing their toxical effects, will speedily and surely restore the patient to health by dispelling the said maladies. Good instances of such homologous cures are afforded by the common Buttercup, the wild Pansy, and the Sundew of our boggy marshes. It is widely known that the field Buttercup (_Ranunculus bulbosus_), when pulled from the ground, and carried in the palm of the hand, will redden and inflame the skin by the acrimony of its juices; or, if the bruised leaves are applied to any part they will excite a blistering of the outer cuticle, with a discharge of watery fluid from numerous small vesicles, whilst the tissues beneath become red, hot, and swollen; and these combined symptoms precisely represent "shingles,"--a painful skin disease given to arise from a depraved state of the bodily system, and from a faulty supply of nervous force. These shingles appear as a crop of sore angry blisters, which commonly surround the walls of the chest either in part or entirely; and modern medicine teaches that a medicinal tincture of the Buttercup, if taken in small doses, and applied, will promptly and effectively cure the same troublesome ailment; whilst it will further serve to banish a neuralgic or rheumatic stitch occurring in the side from any other cause.