A college text-book of chemistry . these cases the chromium enters into combinationas a trivalent base-forming element, taking the place ofthree atoms of hydrogen in hydrochloric acid in the firstcase, and of three atoms of hydrogen in the sulphuric acidin the second. Molybdenum and tungsten do not formsalts of this character; indeed they seem to be practicallydevoid of basic properties. Uranium, on the other hand,gforms some curious salts which differ from the simplemetallic salts which we commonly have to deal with. 246 COLLEGE CHEMISTRY. EXPERIMENTS. Manufacture of Sulphuric Acid. Experimen
A college text-book of chemistry . these cases the chromium enters into combinationas a trivalent base-forming element, taking the place ofthree atoms of hydrogen in hydrochloric acid in the firstcase, and of three atoms of hydrogen in the sulphuric acidin the second. Molybdenum and tungsten do not formsalts of this character; indeed they seem to be practicallydevoid of basic properties. Uranium, on the other hand,gforms some curious salts which differ from the simplemetallic salts which we commonly have to deal with. 246 COLLEGE CHEMISTRY. EXPERIMENTS. Manufacture of Sulphuric Acid. Experiment 102.—The manufacture of sulphuric acid can heillustrated in the laboratory by means of the apparatus repre-sented in Fig. 44. This consists of a large balloon-flask fittedwith a stopper having five openings. By means of tubes it is con-nected with three small flasks. One of these, a, contains waterfor the purpose of providing a current of steam; another, c, con-tains copper-foil and concentrated sulphuric acid, which give sul-. Fio. 44. » phur dioxide \7hen heated ; and the third, 6, contains copper-foiland dilute nitric acid, which give oxides of nitrogen, mainlynitric oxide, NO. When the nitric oxide comes in contact withthe air it combines with oxygen, forming nitrogen trioxide andH^nitrogen peroxide ; and when steam and snlphur dioxide are ad-mitted to the flask the reactions involved in the manufacture ofsulphuric acid take place. By means of a pair of bellows attachedat d air is supplied. If air is not forced in, the gases becomecolorless, owing to complete reduction of the oxides of nitrogento the form of nitric oxide, NO, which is colorless. If steam isnot admitted the walls of the vessel become covered with crystalsof nitrosyl-sulphuric acid. This is, however, decomposed by anexcess of steam. SULPHUROUS ACID AND SULPHUR DIOXIDE. 247 Experiment 103.—Into a vessel containing ordinary concen-trated sulphuric acid introduce small sticks of wood, pieces ofpaper, and
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