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90 TESTING-. charcoal, and by the red sublimate formed when a compound of selenium is roasted in the open tube. Chlorine and chlorides—Salt of phosphorus is melted with as much oxide of copper as suffices to make a very dark green bead, with which the a SS ay is fused; the flame then assumes a violet co our till all the chlorine is driven off, When the quantity of chlorine is very small the assay must be dissolved in nitric acid, having previously ^ rendered it soluble if necessaiy by fusion with soda on platinum wire ; the solution, diluted with water, on adding nitrate of silver, yields a precipitate of chloride of silver which becomes dark on exposure to the light, is easily soluble m ammonia, but not at all in nitric acid. 7 o me and iodides, treated in the same manner with salt of CT.;°r S f 0 6 C0 PP er > impart to the flame a very oeauutul and intensp dt*ppt» • nr»/i XX'VlQH ivi ih ^ *.1 .1 • . X L ’ I ~ ~ “"‘“ v ^ intense green; and, when heated in the closed , . . ---dphate of potash, they yield violet vapour. In so u ion iodine gives a precipitate with nitrate of silver, like a ot chlorine, which however is soluble with difficulty in ammonia Strong sulphuric acid being poured on an iodide in est tube, a strip of starched paper or cotton in the upper part of the tube will be turned blue. 1 Bromine and bromides, melted in like manner with salt of p osphorus and oxide of copper, impart to the flame a greenish ,, Ue ' Seated with bisulphate of potash in the closed tube, ®y yield vapours of bromine, which are recognized by their ye low colour and peculiar smell. When a mineral containing romine is treated with sulphuric acid in a test tube, a piece of 8 I, U! d paper in the upper part of the tube assumes an orange- } chow colour at the end of a few hours. luonne. When it is present in small quantities, and not as n essential constituent, if the assay be heated alone in the closed a strip of Brazil wood paper in its mouth, the glass i e corroded and the paper become yellow. But when the “° n rme 18 lrl } ar g° quantity, and is chemically combined, the tuV, ^ • mU 1 heated with fused salt of phosphorus in the open i 0 / ri , ° rder to produce the same results. The assay being 06 j . P°wder, mixed with strong sulphuric acid and rri., rme ? a , a 8111 all platinum crucible covered with a plate of noinf , Wlt ^ wax ’ having lines traced upon it with a wooden rndpfl' If ft P aces where the glass is laid bare will be found cor roded if the mineral contained fluorine. thrpp^nnrf aC ‘i' l )ne P art .°f the assay in powder is mixed with nine of bf *1 , adux consisting of two parts of fluorspar and meltimr tho' ji * potash, and melted; at the instant of KXe rf C0mca !?rCOn - The a88a y i8 hcated with n evaporated to dryness; alcohol is then added,