328 
Mr. Knox's experiments and observations 
Experiment 6 . 
400 grains of disintegrated Newry pitch-stone which had 
lost 7,25 per cent, by a red heat, were distilled as usual ; 0,1 
came over of bitumen, which had the smell and volatility of 
naptha. 
Experiment 7. 
100 grains in mass of Meissen pitch-stone (the same as that 
which had been analysed by Klaproth, and for which I was 
indebted to my friend Sir Charles Giesecke, Professor of 
Mineralogy to the Royal Society of Dublin ) were ignited in 
a platina crucible. The colour changed from oil-green to 
greenish white passing into greyish green ; it opened in the 
same manner as the compact Newr} r pitch-stone, showing a 
tendency to slate, the fissures being parallel ; fragments in- 
determinately angular and rhomboidal, and the lustre altered 
from resinous to waxy. It was afterwards fused into a white 
enamel and lost 8 per cent. As Klaproth had lost 8,50 by 
simple ignition, I concluded, erroneously, that it contained no 
bitumen. 
Experiment 8. 
400 grains of pitch-stone from Meissen were distilled as 
usual after ignition : a small quantity of bitumen came over 
which had the smell of naptha, and was more volatile than 
any of the former products. The contents of the retort were 
fused into a greyish white enamel. 
Experiment 9. 
Having ignited 400 grains of Meissen pitch-stone, and after- 
wards distilled them in the usual manner, the receiver having 
