194 M. Berzelius on the Combinations of [Sept. 



greater portion of its saline contents is deposited. The liquid, 

 together with this deposit, is now to be heated, until the whole 

 of the latter, which may consist of a mixture of the neutral and 

 sub-acetates, is redissolved, and the concentrated solution thus 

 obtained is to be mixed with alcohol. After about an hour, 

 there is found deposited a bulky gelatinous looking mass, com- 

 posed of an aggregation of minute crystals. These are to be 

 collected upon a linen cloth, and thoroughly washed with alco- 

 hol. When dry, they have rather a pale blue colour. — b. A 

 boiling-hot aqueous solution of the neutral acetate of copper is 

 to be mixed with ammonia, so long as the precipitate thereby 

 produced continues to be redissolved. The liquid is then to be 

 filtered. On cooling, it deposits an irregular uncrystallized 

 mass, and alcohol separates from the cold supernatant liquid a 

 considerable quantity of the same compound, in the form of 

 excessively minute crystalline scales. The salts thus obtained 

 must be washed with alcohol, in order to free them from any 

 adhering portions of the neutral salt; after this treatment, 

 caustic potash disengages from them no traces of ammonia. 

 If, during the preparation of this salt, the solutions are em- 

 ployed in a state of too great dilution, there separates, both 

 by evaporation, and by the addition of alcohol to the solution 

 of the neutral salt, a quantity of the insoluble sub-salt, which, 

 when obtained in this manner, cannot be distinguished by its 

 external appearance, from the soluble sub-sait precipitated by 

 alcohol. 



The salt, prepared by either of these processes, when ex- 

 posed for some hours in the state of a fine powder to a tempe- 

 rature of 140°, lost in different experiments 9 - 5, 10, and 1U'3 

 per cent, of its weight. The residue, which had acquired by 

 this treatment a greenish tint, was boiled for an hour in water 

 along with hydrate of barytes: the mixture was then filtered, 

 and the oxide of copper washed. The filtered liquid was freed 

 from its excess of barytes by a current of carbonic acid gas, 

 after which it was evaporated to dryness with a moderate heat. 

 The acetate of barytes, redissolved in water and filtered from 

 the insoluble carbonate, gave with sulphuric acid 84 of sulphate 

 of barytes, representing 36*8 of acetic acid. The oxide of 

 copper was dissolved from the filter by an excess of muriatic 

 acid. The solution, after filtration, was heated nearly to ebul- 

 lition, and a slip of polished iron plate was introduced into it, 

 with a view to precipitate the copper. The metallic copper, 

 after having been thoroughly washed and dried, was transferred 

 into a small apparatus prepared for this experiment, in which it 

 was ignited, first in a current of atmospheric air, in order to 

 burn away the charcoal deposited by the iron, and afterwards in 

 a current of hydrogen gas, in order to reduce the oxide of cop- 

 per. In this manner, I obtained 34*35 of metallic copper, 



