SILVER MERCURY. 193 



2. Pour a concentrated solution of bismuth into water: a white 

 precipitate of a bismuthyl salt is formed. (See explanation above.) 



3. Add to bismuth solution ammonium or sodium hydroxide, or 

 carbonate : a white precipitate of bismuth hydroxide, Bi(OH) 3 , or of 

 bismuthyl carbonate is produced. (See explanation above.) 



4. Potassium iodide precipitates brown bismuth iodide, BiI 3 , solu- 

 ble in excess of the reagent. 



5. Potassium dichromate precipitates yellow bismuthyl dichromate, 

 (BiO) 2 Cr 2 O 7 . 



6. A small quantity of bismuth or of any bismuth compound, 

 mixed with sulphur and potassium iodide, and heated upon charcoal 

 before the blow-pipe, forms a scarlet-red incrustation of bismuthyl 

 iodide, BiOI. 



29. SILVER MERCURY. 



Silver, Ag = 1O7.7 (Argentum). This metal is found sometimes 

 in the metallic state, but generally as a sulphide, which is nearly 

 always in combination with large quantities of lead sulphide, such 

 ore being known as argentiferous galena. The lead manufactured 

 from this ore contains the silver, and is separated from it by roasting 

 the alloy in a current of air, whereby lead is oxidized and converted 

 into litharge, while pure silver is left. 



Silver is the whitest of all metals, and takes the highest polish ; 

 it is the best conductor of heat and electricity, and melts at about 

 1000 C. (1832 F.) ; it is univalent, and forms but one series of salts; 

 it is not aifected by the oxygen of the air at any temperature, but is 

 readily acted upon by traces of hydrosulphuric acid, which forms a 

 black film of sulphide upon the surface of metallic silver. Hydro- 

 chloric acid scarcely acts on silver, nitric and sulphuric acids dis- 

 solve it. 



QUESTIONS. 271. What are the properties of lead and from what ore is it 

 obtained? 272. What is litharge, and how does it differ from red lead? 273. 

 Give the composition of nitrate, carbonate, and iodide of lead ; how are they 

 made? 274. State the analytical reactions for lead. 275. How is copper 

 found in nature? 276. How many oxides of copper are known; what is their 

 composition, and under what conditions are they formed ? 277. What is " blue 

 vitriol ; " how is it made, and what are its properties ? 278. How does ammo- 

 nium hydroxide act on cupric solutions ? 279. Mention tests for copper. 280. 

 What is the composition of subnitrate and subcarbonate of bismuth ; how are 

 they made from metallic bismuth, and what explanation is given in regard to 

 their constitution ? 



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