WRITINGS OF JAMES SMITHSON. 103 



obtained by means of copper. What its advantages would 

 be above that from cobalt, it is for artists to decide. 



Intent upon the blue smalt, it unfortunately did not occur 

 to me to examine, till I had washed nearly the whole of it 

 away to waste, what was the glutinous matter which had 

 been so true to its office for no less a period than 3,500 

 years ; for the colours were as firm on the stone as they can 

 ever have been. 



A small quantity of it recovered frDm the water did not 

 seem to form a jelly on concentrating its solution ; or to 

 produce a precipitate with galls. I imagined its vegetable 

 nature ascertained by its ashes restoring the colour of red- 

 dened turnsol paper, till I found those of glue do the same. 



The employment of powder of charcoal for a black would 

 seem to imply an unacquaintance with lamp-black, and, per- 

 haps, with bone black, and that of copper to colour glass 

 blue, a deficiency of cobalt. And if the glutinous matter 

 should prove, on a future examination, to be vegetable, our 

 glue being then possessed may, perhaps, be deemed ques- 

 tionable. 



SOME OBSERVATIONS ON MR. PENN'S THEORY 



CONCERNING THE FORMATION OF THE 



KIRKDALE CAVE. 



From Thomson's Annals of Philosophy, Vol. XXIV ; New Series, Vol. 

 VIII, 1824, p. 50. 



June 10, 1824. 



SIR: No observer of the earth can doubt that it has 

 undergone very considerable changes. Its strata are every- 

 where broken and disordered ; and in many of them are 

 enclosed the remains of innumerable beings which once 

 had life ; and these beings appear to have been strangers to 

 the climates in which their remains now exist. 



