BISMUTH COMPOUNDS. 39 6. ес precipitate of iodide of bismuth), and on adding a acetate or nitrate of lead, the iodide of lead which tates will have a brown or red instead of its usual color, from the presence of iodide of bismuth. If ecipitate be dissolved by heating the liquid and addew drops of dil. hydrochloric or acetic acid, it will lize out in very beautiful brown or red scales as the on cools. excellent confirmatory test for bismuth consists in to the original solution some protochloride of tin us chloride, prepared by boiling a fragment of tin rong hydrochloric acid) and an excess of potash, when precipitate of bismuthous oxide, BiO, is obtained. the stannous chloride produce a gray or white pre, becoming dark gray on adding potash, it is probably the presence of mercury. regre ASSO If Metallic Bismuth, Bi, is a brittle metal with a faint Hlection. It does not dissolve in hydrochloric acid, olves in diluted nitric acid, on boiling. , or } Composition. Oxide of bismuth, nitric acid, water. Oxide of bismuth, chloride of bismuth, water. white, BiN,O.H2O, is insoluble in water, but in hydrochloric acid. When heated in a dry glass 7), it evolves moisture, which condenses in drops ool part of the tube, and brown vapors of nitric lution ing a 5 white, BIOCI, is also insoluble in water and soluble white sometimes consists of basic carbonate of lead d). in hydrochloric acid. It may be dissolved in nitric acid tested for chlorine with nitrate of silver (Table H). 30. In order to be quite sure of the presence of n in a solution, it must be boiled with metallic coppe nitric acid be present, which would dissolve the copp must be neutralized by adding a slight excess of am (5); enough dilute hydrochloric acid must then be ad destroy the odor of ammonia, even after shaking, and or three slips of bright copper introduced. On boilin copper will acquire a bright silvery coating, and if rinsed with water, dried in filter-paper and heated in tube (17), a gray crust of minute globules of mercur be formed upon the side of the tube, uniting into globules when rubbed with a glass rod or a wooden Bismuth also deposits upon the copper, but forms a du coating. When mercury is present in the form of cyanide १ cury, it would generally escape detection until the with hydrochloric acid and copper, at the end of Talu * Nitric acid converts mercurous compounds into mer pounds; hence, if this acid should have been used to di original substance, the latter may possibly have been a 1 compound (13). MERCURY COMPOUNDS. 41 rosive Sublimate, HgCl,, is sold either in shining white ransparent masses or as a white crystalline powder. It ves readily when boiled with water, and crystallizes strong solution in white needles. When heated in a tube (17), it melts very easily to a perfectly clear which crystallizes in fine needles on cooling. By uing the heat, it is boiled away in vapor which has a ly suffocating effect upon the nose. milion, HgS, is known by its bright red color. It is pole in water, and in hydrochloric or nitric acid sepabut it dissolves in a mixture of the two acids, with ion of spongy flakes of sulphur. habar, HgS, the chief ore of mercury, is generally met dark brown very heavy hard masses, which become en scraped with a knife. In its relation to solvents bles vermilion. ful grac Oxide of Mercury, HgO, is a bright red shining insoluble in water, but soluble in hydrochloric acid. It 2sso Precipitate, HgCINH,, is a heavy white earthyIf substance, insoluble in water, but soluble in hydroacid. When boiled for some time with water, it yellow. On boiling it with potash, it evolves the ammonia. ate 2 uric Iodide, or Biniodide of Mercury, HgI,, is a powder, insoluble in water, but dissolved by boiling loric acid. When heated on a slip of glass, it beright yellow, and passes off in yellow fumes. The powder becomes red when rubbed with a glass rod. ric Cyanide, or Cyanide or Bicyanide of Mercury, forms white prismatic crystals which dissolve in ater. When heated in a dry tube (17) they helt, and evolve cyanogen, which may be recogis odor and by its burning with a pink flame. A idue is left at the bottom of the tube, and the of the tube is covered with a gray deposit of merhunites into globules when rubbed with a match. , or a lution ing 42 REINSCH'S AND MARSH'S TESTS FOR ARSENIC. 32. The carbonate of ammonia is to be added in ed so that the smell of ammonia is quite perceptible on wa. the liquid; otherwise the sulphide of arsenic would dissolved and might be mistaken for that of tin. It is better to collect a little of the precipitate upon a to wash it once or twice with water (16), and to pour warm carbonate of ammonia over it. If there be any whether the precipitate has been dissolved, test a little solution in carbonate of ammonia with excess of hydrog acid, when sulphide of arsenic will be separated in flakes. 33. Should any confirmatory test be required for ar either Reinsch's test or Marsh's test may be employed Reinsch's test for arsenic.-Boil a little of the c substance with excess of hydrochloric acid and a few of bright copper for a minute or two. The copper d the arsenic from the solution, and a dark gray co of arsenic with copper is formed upon the surface Rinse these with a little water, dry them cu strips. FIG. 17. paper, and heat them gen to consist of octahedral crystals (fig. 17). 34. Marsh's test for arsenic.-Dissolve the su possible, in water or hydrochloric acid. If it be in these, dissolve it in nitric acid, evaporate the soluti ness in a small dish, and redissolve the residue in v a little hydrochloric acid. f p a MARSH'S TEST FOR ARSENIC. ange an apparatus as represented in FIG. 19. α FIG. 18. B 43 els roduce into the bottle enough granulated zinc* to cover tom, fill the bottle about one-third with water, and o dilute sulphuric acid, through the funnel-tube (the end of which must dip beneath the water) until modeulprvescence, from the evolution of hydrogen gas, takes regra Keep the tube as far away from a flame, because the Siss It now filled with an explosive mixture of hydrogen Rssol Incline the gas-bottle and hold a small test-tube If tube b, as represented in fig. 20, for about a minute, ate withdraw it, keeping its mouth downwards, and apply ame; if it explodes, the hydrogen in the bottle is still nulate zinc, melt it in an iron ladle, stand upon the pour the melted metal, in a thin stream, into a pail of ding on the floor. |