BLACK SANDS OF PARACALE. 939 
addition of silver and lead, the silver-gold bead parted, and the 
gold weighed after the usual annealing. 
In some of the tests the mercury after amalgamation was 
badly floured, and considerable difficulty was met in collecting the 
amalgam by panning. This was generally overcome by the ad- 
dition of a little nitric acid which cleaned the floured mercury 
and permitted the minute specks to run together into larger 
globules which were easily panned out. The addition of fresh 
mercury was also tried and found very beneficial in collecting 
the mercury and amalgam. 
Various kinds of apparatus were tried to see if the mercury 
would settle to the bottom of a cone and there be drawn off, 
but when the mercury was floured these proved of little ad- 
vantage. When emptying the bottle, it was customary to invert, 
revolve rapidly, and then let the mercury drop out into a pan, 
whereas the pulp was emptied into a separate pan. It was 
always necessary to collect the mercury in this separate pan 
as some was always floured. 
The percentage of gold saved in many cases is based on the 
actual recovery and not on the assay of the tailings. It will be 
noted that in some cases there is gold unaccounted for by the 
gold saved and assay of the tailings. This is in part due to the 
variations in the samples, but it is also due to an actual loss of 
gold in the process. Some of this loss can be traced to the 
retention of gold by the bucking board, but where excessive it 
probably occurred in the wash water. In making amalgamation 
tests, there was a marked tendency of the gold and floured 
mercury to float off the pan and be lost in the water. At first 
the precaution of carefully settling the slimes was not taken, and 
the losses in some of the tests are thus accounted for. This is 
important as it indicates that in practise great care must be 
exercised in panning the borings of the placer test-holes. It 
shows that a large percentage of the fine gold in those borings 
will not be caught by the ordinary methods of panning. In 
order to prevent this loss, it was found necessary to agitate the 
water and tailings very thoroughly, to allow it to settle for 
twenty-four hours, and to decant and boil the residue to dryness. 
In order to find the amalgamable gold on each screen, the test 
described under magnetic separation (Tables XIV to XVII) was 
made, and by rearrangement the following is shown: 
