The substances used for colouring purposes are more liable to be positively deleterious. While such colouring agents as caramel, turmeric, litmus, saffron, beet-juice, indigo, and some of the coal-tar dyes may be considered comparatively harmless, there can be no question in regard to the very objectionable character of certain other pigments which are sometimes employed: these are mainly inorganic, and include plumbic chromate, salts of copper and arsenic, zinc-white, barium sulphate and Prussian blue. Another occasional form of adulteration to which some kinds of confectionery are exposed, is the admixture of artificial flavourings, such as “pear essence” (amylic and ethylic acetates), “banana essence” (a mixture of amylic acetate and ethylic butyrate), and oil of bitter almonds, or its imitation, nitro-benzole. A preparation known as “rock and rye drops,” which had acquired a great popularity among school children in several of our large cities, proved upon analysis to consist of a mixture of glucose, flour, and fusel oil. The examination of candy and other forms of confectionery usually embraces the determinations of glucose, starch, flour, colouring and flavouring agents, terra alba, and mineral admixtures generally. The detection and estimation of glucose has already been described under Sugar. Starch and flour are readily detected upon treating a minute portion of the suspected candy with a little water and submitting the mixture to a microscopic examination, when, in their presence, the insoluble residue will exhibit the characteristic forms of starch granules. The insoluble portion of the sample may also be tested with a solution of iodine. The proportion of starch can be determined by boiling the matter insoluble in water with dilute sulphuric acid, and estimating the amount of glucose found, by means of Fehling’s solution. Coal-tar and vegetable compounds used for colouring purposes, can often, be recognised by means of their behaviour with reducing and oxidising agents, by their solubility in spirits and other menstrua, and by the application of dyeing-tests. Thus vegetable colours may sometimes be identified upon boiling mordanted cotton yarn in a bath prepared from a portion of the sample containing the colouring matter, and slightly acidulated with acetic acid. This process will likewise generally reveal the presence of aniline dyes, unmordanted woollen cloth being substituted for cotton, and a neutral bath being employed. The inorganic pigments used for colouring candy are usually to be sought for in the ash obtained upon incineration.