or GOLD (AJvD OTHEE IklETALS) TO LIGHT. 
173 
held by any special chemical attraction to, or combination with, the glass ; for a touch 
with a card, a feather, or the finger, was sufficient to remove them at once, and if rubbed 
off with a point of wood, they coated it with brilliant metallic gold. 
Again, though these particles are so finely divided that they pass easily through ordi- 
nary filters, still a close filter catches some ; and if a ruby fluid be passed through again 
and again, the paper at last becomes of a rosy hue, because of the gold which adheres 
to it ; being then well washed, and, if needful, dried, the gold is again ready for experi- 
ment. Such gold paper, placed across the middle of the dark tube and examined by 
transmitted light, was of the same ruby tint as when looked through in the open air. It 
was unaffected by salt or brine, though these, added to the rosy fluid which had passed 
the filter, instantly changed it to Aiolet-blue. Portions of the paper were put into sepa- 
rate glasses with brine, solutions of hydi’ochloric, nitric and sulphuric acids, ammonia, 
potassa, soda and sulphuretted hydi’ogen, but no change occurred with any of them in 
two days. On the other hand, a very dilute solution of chlorine immediately turned 
the ruby to blue, and then gradually dissolved the gold. A piece of the ruby paper 
immersed in a strong solution of cyanide of potassium suffered a very slow action, if any, 
and remained unaltered m colour ; being brought out into the air, the gold very gra- 
dually dissolved, becoming first blue. A portion of the ruby paper Avas dried and heated 
in oil until the oil and the paper began to change their hue ; the gold had not altered 
in its colour or character. Another portion Avas heated in the vapour of alcohol and 
also of ether until the paper began to alter ; the gold remained unaltered. A blue fluid 
being passed oftentimes through a filter gave a blue paper, Avhich, being washed and 
tried in the same manner, was found to contain particles unchanged by the simple acids 
or alkalies, or by heat or vapours, but dissohing, as gold Avould do, in chlorine or nitro- 
muriatic acid. These tests are, I think, sufficient to prove the metallic nature and per- 
manence of the gold as it exists in the ruby, amethystine, violet, and other coloured 
fluids. 
The production by such different agents as phosphorus, sulphide of carbon, ether, 
sugar, glycerine, gelatine, tartaric acid, protosulphate of iron and protochloride of tin, of 
gold fluids all more or less red or ruby at the commencement, and all passing through 
the same order of changes, is again a proof that only gold was separated ; no single one 
or common compound of gold, as an oxide or a phosphide, could be expected in all these 
cases. Many of the processes, very different as to the substances employed to reduce the 
gold, left good ruby films adhering to the glass vessels used, presenting all the characters 
of the gold described akeady ; this w^as the case with phosphorus, sugar, tartaric acid, 
protosulphate of iron, and some other bodies. 
Again, the high reflective poAver of these particles (unalterable by acids and salts), 
Avhen illuminated by the sun’s rays and a lens, and the colour of the light reflected, is in 
favour of their metallic character. So also is their aggregation, and their refusal to 
return from blue, violet or amethystine to ruby ; for the cohesive and adhering force of 
the gold particles and their metallic nature and perfect cleanliness is against such a 
