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1888.) 107 [Davis, 
the condition of the chlorine, from a free to a combined state, and this 
metal remains in solution, as does every contained substance, which is 
soluble in ClH. 
That the free chlorine is thus converted into the combined state is shown 
by the following experiment, which was made after the carbon had con- 
verted two hundred times its volume of chlorine, or the filter of 80 gallons 
of coal had received 8750 gallons of the chlorine solution, carrying about 
twice its volume of gas : 
Of the running solution two samples were taken, one from the surface 
before it entered the coal, the other from the bottom after it had passed 
through the filter; from the first, the chlorine acted powerfully on the 
senses ; in the second, no odor was perceptible. 
To equal portions of the two samples were added nitrate of silver, the 
precipitated chloride was collected, washed and dried with due precautions, 
and the weights of the two precipitates exactly corresponded; the one 
measuring the sensible, the other the combined chlorine. 
In only one experiment of long-continued action, has a sensible diminu- 
tion of the carbon been observed ; further and more exact determinations 
than could be made in a mine laboratory are required to establish this 
point. 
Neither has it been determined to what extent the deposit of gold can be 
carried by this method, the button of gold now exhibited weighing eigh- 
teen and a half pennyweights was recovered from the ash of two ounces 
of charcoal ; the filter from which it was taken seemed to have lost none of 
its activity. The grains from the surface of this filter yielded the pseudo- 
morphs of gold which are before you, and the weight of the gold is above 
One-third the weight of carbon, which has been removed. 
As affecting this question, and possibly of interest to the chemist, the 
following observation was made on the action of dilute 50% on charcoal 
taken from a filter after being subjected to the action of chlorine for six 
days : 
With the thought that washing this carbon with dilute SO® might clean 
the coal and increase its activity, a portion of it was placed in a glass per- 
colating tube, and the above acid passed slowly through it. The solution 
from the bottom came away of a dark brown color, but retaining its trans- 
parency ; on passing this through filtering paper no deposit was retained, 
showing that the color was not owing to dust of the coal. The solvent 
action of the acid continued as long as it was applied, and until the size of 
the carbon grains were sensibly diminished, when the acid solution was 
replaced by a current of cold water. Now the escaping fluid was almost 
black, being many shades darker than the acid solution, This when 
largely diluted was of a rich brown color, and perfectly transparent. The 
carbon grains were rapidly diminishing in size, and seemingly entirely 
soluble, when the process was interrupted to test the power of the remain - 
Ing contents of the tube on an auric chlorine solution. 
On passing such solution through the residuum, it was found to have 
