This group of nostrums consists of those which are put forward for the cure of kidney troubles, or conditions of ill-health commonly, but as a rule erroneously, attributed by the public to kidney disease. Several of these are in the form of pills, while others are liquids. The two principal drugs employed are oil of juniper and potassium nitrate (nitre or saltpetre), separately or together; in some cases aperients are added. Altogether extravagant claims are made for some of the articles, as is usual, of course, with proprietary medicines; this point is dealt with more fully in the descriptions of individual preparations. In analysing complex mixtures, such as some of these nostrums are, it is, of course, not possible to attain the same precision as when dealing with medicines which consist chiefly of inorganic salts, as in the case of nostrums for epilepsy, dealt with in another chapter. A vegetable extract containing no definite active principle, such as, for instance, extract of taraxacum (dandelion), cannot be identified by any direct test; if such an extract is mixed with another, with a powdered drug, or an essential oil, its identification with perfect certainty may become almost impossible. The large variations, again, which may occur in the proportion of solid matter in a tincture or infusion, as well as the variations in the relative proportion of the different constituents of drugs, prevent the results of analysis being translated with certainty into the formula from which the mixture was compounded. These considerations apply to several of the articles described in this chapter. While the principal ingredient or ingredients in each case can be ascertained with little or no possibility of error, the subsidiary ingredients in some cases cannot be determined with the same confidence; we have endeavoured to indicate in each case the possibility of such minor errors. Full use has been made of check methods, by compounding mixtures according to the formulæ obtained by analysis and comparing them with the originals. DOAN’S BACKACHE KIDNEY PILLS. These pills, of American origin, which have been very extensively advertised for some years, are sold in boxes price 2s. 9d., containing 40 “kidney pills” and 4 “dinner pills.” They were described on the wrapper of the package as a Specific for kidney complaints and all diseases arising from disorder of the kidneys and bladder. Cure Backache, Weak Back, Rheumatism, Diabetes, Congestion of the Kidneys, Inflammation of the bladder, Gravel, Bright’s Disease, Scalding Urine, and all Urinary troubles. A circular was enclosed with the box, in which a dissertation on “Diseases of the Kidneys and Bladder” was given, together with directions for taking the pills for various complaints. The following extracts are taken from the circular: