on the Newry pitch-stone , &c. ggg 
pany the solutions of that substance, and to modify the colour 
and magnetic properties of the metal. 
It is necessary to observe that, unless the beak of the retort 
be kept almost at a red heat, as far as the mouth of the re- 
ceiver, the whole of the bitumen will not be obtained. 
This quality renders it easy, however, to ascertain the pro- 
portion in which it exists in the stone ; a heat of ignition ex- 
pelling only the water, and the loss of weight by fusing after 
ignition, giving pretty exactly the quantity of this curious 
inflammable matter, which appears to vary considerably in 
the different specimens from the same vein. 
I have not yet been able to examine it with sufficient ac- 
curacy, partly from want of time, and partly from the diffi- 
culty of analysing so small a portion of the substance as I 
have yet been able to collect. I hope, however, to renew 
the investigation next winter. If it should be found to be a 
new substance, I propose to call it newrine. I should not be 
surprised, however, judging from the smell, and its being 
separable from water by evaporation, if it were found to con- 
tain nicotine in combination with naptha. 
Pumice . 
The formation of this substance artificially , is rather an 
interesting circumstance, if it be new; and may throw some 
light upon its natural formation. 
That it is a perfect pumice, in appearance and qualities, 
what I have already mentioned puts almost out of doubt. It 
has the colour, levity, and magnetic properties of the real 
pumice, and deceived artists to whom I presented it as such. 
An eminent paper stainer, who is in the constant use of that 
