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One gram of an oxide of iron is fused with potassium acid sulphate and the fusion dissolved in acid. The iron is reduced with stannous chloride, mercuric chloride is added, and the iron titrated with a normal K Cr O solution. 12.94 cc. were used. What is the formula of the oxide, FeO, Fe O , or Fe O ? !Answer!: Fe O . !Answer!: Monovalent.
The difference between free and combined oxygen may also be shown by decomposing other compounds of oxygen, such as water and mercuric oxide. Close the test tube with a tight-fitting stopper which bears a glass tube of sufficient length and of the right shape to convey the escaping gas to a small trough or pan partly filled with water, on the table.
Erlenmeyer flasks, cover them with watch-glasses, and bring the acid just to boiling. Remove them from the flame and drop in the portions of wire, taking great care to avoid loss of liquid during solution. Dilute with 150 cc. of water and cool !completely!. When cold, add rapidly about 30 cc. of mercuric chloride solution.
Sulphurous acid and zinc chloride also failed to destroy all the germs of infection. Chlorine, bromine, and mercuric chloride gave the best results; solutions of mercuric chloride, nitrate, or sulphate diluted to 1 part in 1,000 destroy spores in ten minutes. R. Koch. By N.B. WOOD, Member of the Civil Engineers' Club, of Cleveland.
The latter object is accomplished by oxidation to stannic chloride by means of mercuric chloride added in excess, as the mercuric salts have no effect upon ferrous iron or the bichromate. The reactions involved are: 2FeCl + SnCl > 2FeCl + SnCl SnCl + 2HgCl > SnCl + 2HgCl The mercurous chloride is precipitated.
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