A popular chemistry; . n long enough to remove all tuhich hasremained in the water-pipes during the night; andwhen the H20 is let on again after it has been shutoff for awhile, leave the faucet open until the pipeis thoroughly washed. The Test of Pb is H2S, forming lead sulphide,PbS. The following is an interesting illustration:Thicken a solution of lead acetate with a little gum-arabic, so as not to flow too readily from the pen,and then make any sketch which your fancy maysuggest. This, when dry, will be invisible. Whenit is to be used, dampen the paper slightly on thewrong side, and then di
A popular chemistry; . n long enough to remove all tuhich hasremained in the water-pipes during the night; andwhen the H20 is let on again after it has been shutoff for awhile, leave the faucet open until the pipeis thoroughly washed. The Test of Pb is H2S, forming lead sulphide,PbS. The following is an interesting illustration:Thicken a solution of lead acetate with a little gum-arabic, so as not to flow too readily from the pen,and then make any sketch which your fancy maysuggest. This, when dry, will be invisible. Whenit is to be used, dampen the paper slightly on thewrong side, and then direct against it a jet of picture will at once blacken into distinctness.* Compounds. — Lead Oxide, PbO, the well-knownlitharge, is formed by heating Pb in a current of * A delicate test for the presence of lead in water is this: Add a few-drops of acetic acid and then a small pinch of powdered bichromate ofpotassium (K2Cr207). If Pb is present, a yellow turbidity will appear. 164 INORGANIC CHEMISTRY. Fra. air.* Lead Dioxide, Pb02, is formed by oxidizingPbO. A mixture of the two, called red-lead, is usedfor coloring red sealing-wax, and as a paint. Lead Carbonate (PbC03), White-Lead, consistsof basic lead carbonates, and is made as follows:Thousands of earthen pots fitted withcovers and containing weak vinegar(acetic acid) and a small roll of Pb, arearranged in piles, and then coveredwith tan-bark. The acetic acid com-bines with the Pb, but the C02 formedby the decomposing tan-bark creeps inunder the cover, driving off the aceticacid, and forming lead carbonate. Theacetic acid, thus dispossessed, attacksanother portion of the Pb, but is robbedagain ; and so the process goes on, till the Pb is ex-hausted. White-lead is often adulteratedwith heavy spar, gypsum, etc. Lead Acetate, Sugar of Lead, has asweet, pleasant taste, but is a virulentpoison. Its antidote is Epsom salt, whichforms an insoluble lead sulphate. H20 dis-solves sugar of lead readily. If a piece ofZn,
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Keywords: ., bookcentury1800, bookdecade18, booksubjectchemistry, bookyear1887
