[ 46 ] 
a fifh-fkin or ru flies : I warmed it, and fmeared it 
with wax only ; then took cirnolia (tobacco-pipe 
clay) diverted of its fand, by being dirt'olved in wa- 
ter and poured off, leaving the coarfe heavy parts be- 
hind. After this was dried and powdered, I mixed 
it with a fmall quantity of the yolk of an egg and 
cow’s milk, and made a ground with this on the 
waxed board : this I was induced to try, by know- 
ing that the yolk of an egg will dirt'olve almort all 
undtuous fubftances, and make them incorporate 
with water ; and I apprehended, that a ground, thus 
prepared, would adhere fo much the more firmly to 
the board than the former had done, as to prevent 
its flaking off. The milk, I thought, might anfwer 
two purpoles ; firft, uniting the ground with the 
wax i and fecondly, by anfwering the end of fize, 
or gum-water, and prevent the colours finking too 
deep into the ground, or running one into another. 
When the ground was near dry, I fmoothed it with 
a pallat-knife, and wafhed with milk and egg where 
I had occafion to make it fmooth and even : when 
dry I painted it, mixing the colours with common 
water ; this, on being placed horizontally in an oven, 
only warm enough to melt the wax, flaked from 
the board j but held fo much better together than 
any of the former, that I parted part of it on 
paper. 
Ex PE 
