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or GOLD (AJSTD OTHEE METALS) TO LIGHT. 
Diffused particles of gold-production — proportionate size — colour — aggregation and other 
changes. 
Agents competent to reduce gold from its solution are very numerous, and may be 
applied in many different ways, leaving it either in films, or in an excessively subdivided 
condition. Phosphorus is a very favourable agent when the latter object is in view. If 
a piece of this substance be placed under the surface of a moderately strong solution of 
chloride of gold, the reduced metal adheres to the phosphorus as a granular crystalline 
crust. If the solution be weak and the phosphorus clean, part of the gold is reduced in 
exceedingly fine particles, which becoming diffused, produce a beautiful ruby fluid. 
This ruby fluid is well obtained by pouring a weak solution of gold over the phospho- 
rus which has been employed to produce films, and allowing it to stand for twenty-four or 
forty-eight hours; but in that case all floating particles of phosphorus should be removed. 
If a stronger solution of gold be employed, the ruby fluid is formed, but it soon becomes 
turbid and tends to produce a deposit. When the gold is in such proportion that it 
remains in considerable excess, still the ruby formation is not prevented, and being 
formed it mingles unchanged with the excess of gold in solution. If an exceedingly 
weak solution of gold he employed, the production of ruby appears to be imperfect and 
retarded. The nearer the solution is to neutrality at the commencement the better ; 
when a little hydrochloric acid was added the effect was not so good, and the colour of 
the fluid was more violet than ruby. 
If a pint or two of the weak solution of gold before described be put into a very clean 
glass bottle, a drop of the solution of phosphorus in sulphide of carbon added, and the 
whole well shaken together, it immediately changes in appearance, becomes red, and 
being left for six or twelve hours, forms the ruby fluid requued ; too much sulphide and 
phosphorus should not be added, for the reduced gold then tends to clot about the por- 
tions which sink to the bottom. 
Though the sulphide of carhon is present in such processes and very useful in giving 
division to the phosphorus, still it is not essential. A piece of clean phosphorus in a 
bottle of the gold solution gradually produces the ruby fluid at the bottom, but the 
action is very slow. If the phosphorus be attached to the side of the bottle, but always 
beneath the surface of the solution, the streams of ruby fluid may be seen moving both 
upwards and downwards against the side of the glass, and forming films in the vicinity 
of the phosphorus perfect in their golden reflexion, and yet transmitting light of ruby, 
violet, and other tints, thus giving, first a proof that the particles are gold, and then con- 
necting the present condition of the gold with that of the films already described. On, 
the other hand, the phosphorus may be excluded and the sulphide of carbon employed 
alone ; for when it and the solution of gold are shaken together, the gold is reduced and 
the ruby fluid formed ; but it soon changes to purple or violet. 
A quick and ready mode of producing the ruby fluid, is to put a quart of the weak 
solution of gold (containing about 0'6 of a grain of metal) into a clean bottle, to add a 
little solution of phosphorus in ether, and then to shake it well for a few moments : a 
