[D0014AAL], Letter from Cloyd Mason Chapman, John Vincent Miller to Thomas Alva Edison, August 1st, 1900


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[D0014AAL], Letter from Cloyd Mason Chapman, John Vincent Miller to Thomas Alva Edison, August 1st, 1900





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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University


Thomas A. Edison, Esq.,
Orange, N. J.
Dear Mr. Edison :-
After a great deal of experimenting we have now obtained a very much more [content?] and evenly distributed [illegible text] than formally and tried a considerably lower speed of [illegible text]. This reduction of speed of the fan necessitated getting a smaller pulley, which has delayed the running of the smaller sizes of gravel. This pulley arrived today and a run was made on the "under .007" gravel, the results of which have not yet been assayed.
Upon asking the runs with the separator mentioned in our report of July 10th to determine the more efficient method of screening it became evident by the high percentage of gold saved__over 99%- and the low percentage of concentrate _ about 3/4% - that we could increase the range between the different sizes. We screened out some gravel doubling the range of sizes by omitting alternate screens and have made a number of runs with the separator of the larger sizes of gravel. The smaller sizes have not yet been put through the separator because we could not get slow enough speed of fan as we explained above. The results of these runs are quite encouraging but we believe it is still possible to improve them.
The following are the results of all the runs made with the greater range of size, using gravel taken from the mill excavation.
<Tell [illegible] to send 10 or 15 lbs of Experimental Concentrates from Mill Site to try on separator>
<Answered Aug 10/1900> These runs indicate that it will be possible to use this greater range of size and get a low percentage of concentrate and high percentage of gold saved, and we propose to continue these experiments until uniform and satisfactory results are obtained.
At present we divide the gravel into seven sizes as follows: Under .007 : .007 to .012 : .012 to .018 : .018 to .029 : .029 to .047 : 0.47 to .074 : .074 to .119.
Results so far would indicate that there is not enough gold over .074 to warrant the working of the last size but the gold may run coarse in other parts of the mesa so we propose to continue running this size.
Everything is ready to begin running the gravel from the shafts though the mill as soon as we get the sizing and separating processes in satisfactory form.
Mr. Lawson, in a letter to Mr. Burn, says that you expressed yourself as anxious to receive some of our concentrate for trial on the magnetic separator. We would like to know whether you wish some of the concentrate that we are obtaining now in these experimental runs or to wait for some from the regular runs on the gravel from the shafts.
Respectfully yours,
John V. Miller.
Cloyd M. Chapman.
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