Obfervations in Eleclricity. 393 
I painted feveral cards with almoft every colour I had, 
and fent {hocks over them when they were very dry : 
the effects were as follows 
Vermillion was marked with a ftrong black track, 
v 
about one-tenth of an inch wide. 
Carmine received a faint and {lender impreffion, of a 
purple colour. 
Verdigreafe was fhaken off from the furface of the 
card. 
White lead was marked with a ftrong black track, 
not fo broad as that on vermillion. 
Red lead was marked with a faint mark much like 
carmine. 
The other colours I tried were, orpiment, gamboge, 
fap-green, red ink, ultramarine, Pruffian blue, and a few 
others, which were compounds of the above, but they 
received no impreffion. 
It having been infinuated, that the ftrong black mark, 
which vermillion receives from the eledtric {hock, might 
poffibly be owing to the great quantity of fulphur con- 
tained in that mineral, I was induced to make the fol- 
lowing experiment. I mixed together equal quantities 
of orpiment and flower of fulphur, and with this mix- 
(b) The force employed was the full charge of one foot and a half of coated 
glafs. 
VOL. LXVII. Fff true, 
F f f 
