294 VINEGAR, CIDER, AND FRUIT- WINES. 



more strongly it fuses at 536 F. to a clear, oil-like, colorless 

 fluid and decomposes above this temperature, evolving all the 

 compounds usually obtained in the destructive distillation of the 

 acetates of the heavy metals, leaving a residue of metallic lead in 

 a very minute state of division with some charcoal. When this 

 distillation is conducted in a glass tube closed at one end and 

 having the other drawn out for convenience of sealing, at the end 

 of the operation, the well-known lead pyrophorus is made. The 

 particles of metallic lead are so small that, when thrown into the 

 air, oxygen molecules come into such intimate contact with them 

 that ignition is effected from the rapidity with which lead oxide 

 is formed. 



A slight decomposition occurs when the neutral salt is exposed 

 to an atmosphere of carbonic acid, carbonate of lead being formed ; 

 the portion of acetic acid thus liberated protects the remainder 

 from further change. 



Cold solution of sugar of lead is not immediately changed by 

 ammonia ; by adding, however, a strong excess, sexbasic acetate 

 of lead is gradually separated ; on boiling yellow-red crystalline 

 lead oxide is precipitated. 



The introduction of chlorine gas into a solution of sugar of 

 lead produces in a short time a brown precipitate of plumbic di- 

 oxide ; bromine acts in a similar manner, but on account of its 

 insolubility iodine produces scarcely any effect. 



Solution of calcium chloride at once produces a yellow pre- 

 cipitate, which gradually becomes brown. 



Sugar of lead containing considerable copper has a bluish ap- 

 pearance ; if the content of copper is small, it is recognized by the 

 solution acquiring a blue coloration with ammonia, or, still better, 

 by mixing the solution of sugar of lead with an excess of solution 

 of Glauber's salt and testing the filtrate with potassium ferro- 

 cyanide ; a dark red precipitate indicates copper. 



Sugar of lead, as well as the basic lead salts to be mentioned 

 further on, possesses poisonous properties. 



Sugar of lead is chiefly used for the preparation of aluminium 

 acetate as well as of other acetates. Large quantities of it are 

 also consumed in the manufacture of colors, for instance, of neu- 

 tral and basic lead chromate, chrome yellow, chrome orange, and 



