212 CORRESPONDENCE. 



and Copal, but not what is the positive distinguishing difference between them . 

 I think, however, an experiment of my own, to be subsequently detailed, will 

 accomplish this. 



For example, Amber and Copal are vegetable gums, having the same specific 

 gravity, and are similar in colour ; they both burn with a bright flame, giving off a 

 resinous odour. Both are electric, and, lastly, both of them are insoluble in 

 water (at any temperature), but soluble in alcohol. Sometimes, however, the 

 fracture of Amber is of a well-defined conchoidal form, whilst Copal is rarely 

 even imperfectly conchoidal. Yet to the majority of students there is a doubt 

 as to the identity of these interesting substances, whilst they have not hitherto 

 had data sufficient to demonstrate their actual difference. At least such is my 

 impression ; and I say so because the works of mineralogists leave the subject 

 in the state before mentioned, enumerating the characters common to both, but 

 not pointing out the positive difference between them. 



I had, however, a few years since, the satisfaction to obtain a test whereby to 

 distinguish them, and which renders it necessary that they have some difference 

 in their chemical properties. I may mention that I was trying an experiment 

 with a piece of opaque amber, for the purpose of rendering it transparent. The 

 following was the process : — A piece of opaque Amber, round which some pack- 

 thread was tied, was suspended in linseed oil in a small saucepan, and the oil 

 was gradually heated (the Amber remaining in it all the while) ; when it was 

 removed, the only alteration which had taken place was simply that the Amber 

 was cracked on its surface, in small and superficial fissures, the substance being 

 otherwise unchanged. I then took a bit of Copal, and submitted it to the same 

 process, and on examining it shortly afterwards, the Copal was softened, and sub- 

 sequently dissolved. 



Legend of the Bloody Stones. 



Within the immediate vicinity of Conisborough Castle there is a small rivulet, 

 in which are to be seen many stones having dark red patches on the surface. I 

 am told that there is a tradition current among the lower classes of the village 

 and its vicinity, that at some remote period of our history there was a sangui- 

 nary battle fought at this spot, and that such a quantity of human blood was 

 spilled on the occasion, that all the stones become deeply saturated with it ; and, 

 although the water has continued to ripple over them for more than two cen- 

 turies on its way to the Don, yet it has not been able to wash away the human 

 gore — hence the designation " bloody stones." I have now some of these bloody 

 stones lying before me,* and will describe them. They are pieces of carbonate 



* The stones were given to me by Mr. Joseph Foster of this town, to whom I am indebted 

 for the substance of the above legend. 



