Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 4, 1802).djvu/371

Rh into small quadrilateral segments, that will adhere to the paper on which it is sprcead.

In order to detect the , or sugar of , 10 or 12 drops of a solution of yellow and quick-lime should be poured into a glass of wine: if the colour of the fluid change, and become successively dark-reddish, brown, or black, it is an evident proof of its being adulterated with lead.—As orpiment, however, contains a large proportion of, it is apt to produce effects equally fatal with those resulting from the sugar of lead: we shall, therefore, subjoin a few other tests, which are perfectly harmless. Thus, ("History and Memoirs of the Royal Academy of Sciences at Paris, for the year 1787," &c.) directs a few drops of vitriolic acid, or of pure saccharine acid, to be introduced into a certain portion of the suspected liquor. These will cause the lead to sink to the bottom of the glass, in the form of a white powder; which, if laid on a piece of solid charcoal, may be reduced to metallic globules, by means of the lamp and blow-pipe. Nevertheless, he preferably recommends a solution of hepatic gas in distilled water: this, he observes, will, on being added to wine sophisticated with lead, produce a black sediment, and thus shew the smallest quantity of that metal; whereas, in pure wine, no precipitation will take place:—the precipitate of lead may be readily distinguished from that of other minerals, by its deep colour.

Dr. ("Chemical Essays," vol. iii.) advises 1 oz. of quick-lime, and half an ounce of flowers of sulphur, to be boiled in one pint of water: when the liquor is cold, it must be carefully bottled up; and, on adding a few drops to the wine, or cyder, impregnated with lead, the colour of the whole will become of a lighter or deeper brown, according to the quantity held in solution. But, as this test also precipitates iron, when dissolved in any vinous fluid, we think the following probatory liquor may be preferably employed: it was invented and published in 1791, by Dr., but the merit of his claim has lately been assumed by an obscure German chemist in London; and we understand, that the recipe for this test has been surreptitiously sold to a French speculator, on whose account it is now retailed by several venders, under his directions. Dr. H.'s original test has, within the last three or four years, been simplified and improved; so that it is now prepared in the following manner:—Let one dram, of the dry liver of sulphur, and two drams of cream of tartar be shaken in two ounces of distilled water, till the whole become saturated with hepatic gas: the liquor must now be filtred through blotting-paper, and kept in a phial closely stopped.—In order to try the purity of wine, from 16 to 20 drops of this test are to be poured into a small glass: if the wine become only turbid, with white clouds, and a similar sediment be deposited, it is then not impregnated with any metallic ingredients. Should it, however, turn muddy or black; its colour approach to a deep red; and its taste be at first sweet, and then astringent; the liquor certainly contains the sugar, or other pernicious preparation of lead. The presence of iron is indicated by the wine acquiring a dark-blue cast, similar