480 DE. KIKK ON COPAL. 



depth of 10 inclies, when I soon found small pieces of Animi, but 

 not of the modern sort. There was no Copal-tree In the place 

 where 1 dug ; and the resin had lain there, it may be, for centuries. 

 This led me to examine minutely the outer skin ; and I found, as 

 you will see from the pieces when they arrive, that copal when 

 dug up has no trace of the goose-skin upon it. I am now satis- 

 fied that this is due to a change in the surface of the mass after 

 exposure, when, to a certain depth, an oxidation takes place, 

 or it may be a molelecular change, rendering the skin more 

 brittle than the inner mass. When treated with a solution of 

 caustic soda, this brittle crust softens, and, on drying, cracks to 

 the full depth to which the change has taken place. After dry- 

 ing in the sun, the friable crust may be removed with a hair 

 brush, and then for the first time we see the goose-skin, cha- 

 racteristic of good or fossil AnimL 



When cleaning copal, it may be that each merchant throws 

 away aa much as thirty pounds daily of this dusty resin brushed 

 off the copal, and this they call sand ; but I send you a speci- 

 men to show you that it is genuine resin and, I suspect, of 

 value, at least worth more than being cast into the sea, as is here 

 done. 



On my return home one evening I came upon an old Baobab 

 tree that had been cut down in clearing the ground ; the tree 

 was, on the average, 6 feet in diameter ; it had been cut about two 

 years, and had lived for at least one year after being completely 

 severed from the ground ; now it seemed to have been dead for a 

 year, and was fast rotting. On tearing off* the layers that gaped 

 open and parted from one another far more easily than the bark 

 of other trees from the wood, I found that the last vital act had 

 been to give out a stiff lace-like network of rootlets between 

 each annual layer ; so coarse were these at places as to resemble 

 a fishing-net. These woody plates, separated by layers of matted 



:knes3 from |-| 



growth 



trees of the same sort, which long ago convinced me that the 



Africa 



ascribed to them ; a tree of 6 feet may be 100 years old. In 

 this instance the last-formed circumferential layers were fully as 

 thick as the central. That the central layers 

 annual growth, I think proved by my obser 

 trees, of which I have examined many. 



are 



on young 



