CHEMICAL SCIENCE. 235 



After five or six repetitions of this treatment, the copper receives a 

 brass color ; after from six to ten repetitions, it acquires a fine yellow. 

 If the copper is now to be changed from yellow to brow r n, it must no 

 more be wetted whilst hot ; if, however, it be desired to have it very 

 pale brown, the process must be repeated twenty or twenty-five times. 

 Y\ hen the desired color is attained, the copper is to be laid in clean 

 water, taking care to clean it or dry it rapidly after taking it out. 

 This must be done carefully. The copper is then held over a weak 

 charcoal fire, when the bronze becomes permanent and fire-proof. 



To give a fire-proof, brown, bronze color to brass, the following is 

 the process : - 



j 3 Tj- of an ounce of crystallized verdigris and the same quantity of 

 sal-ammoniac are mixed with 5-Gths of a pint of rain-water, and left to 

 stand form 2 to 3 hours. The brass is then to be rubbed over with it 

 from 2 to 3 minutes, when it becomes green. 1^ pint of rain water is 

 now to be added to the solution. The metal is now held over a char- 

 coal fire, which must not be too strong, until it acquires a copper col- 

 or. It is then again wetted, and left to dry by evaporation. When 

 it has been treated in this manner four or five times, it becomes olive- 

 colored. The heat may now be somewhat increased, but it is neces- 

 sary to be very careful that the metal does not become too hot. When 

 it has been treated nine or ten times in this manner, it becomes brown. 

 As long as any greenish places are to be seen, however, this treatment 

 must be continued, in many cases 20 to 25 times before the required 

 color is obtained. 



If, however, the metal be strong, the materials are to be dissolved 

 in hot rain-water, and the metal rubbed with it immediately until it 

 acquires a fine dark green color ; it is then to be held over a strong 

 charcoal fire, by which means it acquires a fine brown color after 10 

 to 1 2 repetitions of the treatment. It is necessary to be careful that 

 the metal is equally heated throughout. If spots appear, they must be 

 bitten out during the work and polished with brick-dust. Geicerbe- 

 llatt aus Wurlem.j 1852, No. 1. 



ELECTRO-DEPOSITION OF ALLOYS. 



A patent has been recently issued to Messrs. Morris and Johnson, 

 of Birmingham, England, for a method of depositing alloys by elec- 

 tro-chemical agency. The invention consists in the employment of 

 solutions composed of cyanide of potassium and carbonate of ammo- 

 nia, to which are added cyanides, carbonates, and other compounds of 

 metals, in proportions according to the amount of deposit required to 

 be made. 



In order that the invention may be fully understood and carried 

 into effect, the patentees proceed to describe the means pursued by 

 them, as follows : These improvements consist in the employment of 

 solutions composed of carbonate of ammonia or the sesqui-carbonate 

 of ammonia of chemists, and cyanide of potassium, to which are ad- 

 ded carbonates, cyanides, or other compounds of metals, in various 



21* 



