THE ORIGIN OF MOSS GOLD. 293 
The globule was weighed and found to have taken up 6:167 of 
arsenic, the amount was really larger but some of the alloy was 
lost by spirting on solidification. On cupellation of part of this 
globule the loss was equal to 7:5 of arsenic. 
Afterwards larger amounts of gold were converted into arsenide 
in this way. On introducing cold gold into the arsenic vapour it 
became coated with a grey deposit of metallic arsenic, but as it 
became hotter the gold recovered its usual colour and lustre, but 
as soon as the gold became just red hot it rapidly fused down at 
the edges, just as when a strip of lead is held in a flame. In 
dealing with this larger quantity of gold in the large combustion 
tubing (three-quarter inch diameter) it was found necessary to 
use a gas blowpipe as a bunsen was not quite sufficient. 
Experiment 7.—In this case the globule from 1:3627 g. of gold 
was shaken just as it was about to solidify, the whole suddenly 
became solid, with strongly marked crystalline surface and of a 
very bright lustrous gold colour, but cavernous at the base and 
exceedingly brittle. On cupellation it lost weight equal to 4°617/ 
arsenic. 
Experiment 8.—On roasting and fusing a portion of the alloy 
obtained in this experiment ina muffle without cupellation it lost 
weight = 3°297/ of arsenic, although it showed, when fractured, 
grey specks of either arsenic or a grey alloy. 
Lxperrment 9.—In this case aftera globule of the arsenide had 
been formed, fresh supplies of arsenic were pushed down against 
the molten alloy (the supply of arsenic vapour from the bottom 
of the tube being still kept up) when it was apparently rapidly 
absorbed by the fluid alloy, the alloy “ wetted ” the plate of arsenic 
at once, and when the plate was drawn slowly backwards followed 
it as a streak (like water) to about one-third inch in distance. 
As the quantity of arsenic increased the alloy became less fluid 
and less brilliant in lustre; whether much more arsenic was really 
absorbed and whether the arsenic was only volatilized by contact 
with the fluid alloy is difficult to tell. On solidifying, the alloy 
