144 
yellow Oxide, or Sulphur, these being so nicely incorpo- _ 
rated in the mass as not to be easily detected. Most en- 
deaveurs to ascertain the colours of substances first discolour 
‘them, and it is not easy to find and mix the proportions 
by synthesis, although the present advancing state of 
chemical knowledge gives a hope that these things are 
likely to. be discovered in due time. 
The analysis by Klaproth shows no particular colouring 
substance except Iron, as will be seen below; 
Silicaya ss veiw) 2 3S ; 
PUNE vane eth 
Mapnestan ss sot stoae 
UNC need ol hel ee ao 
Oxidemilronyiis" > ax 
Winterreise coe e marlin 
Loss’ 4-.6)-s-cageoes 1 
100°0 
The holes in the Rock of Kinnoul are occasionally lined 
or filled with great variety of coloured substances, perhaps 
including all possible mixtures, except the more brilliant 
reds and crimsons, 
