Minerals of Organic Origin.— Mineral Resins. 91 



r Carbon 72-533 f Carbon 72-322 



C4, H31 Os =\ Hydrogen 8-929 or C4, H30 O3 = \ Hydrogen 9-315 



L Oxygen 18-538 L Oxygen 18-463 



100-000 100000 



I am inclined, therefore, in the mean time to prefer the 

 former of these two C4, Hgj Og, though the discovery of any 

 mixture or impurity in the resin may hereafter show either of 

 the others to be a more correct representation of its elementary 

 constitution. The establishment of the first, C40 H31 Og , from 

 its analogy with the formula for colophony, would appear from 

 theory the most likely, were there not other resins, the analyses 

 of which I have already published, which appear to deviate 

 from the general formula 



^4oH 32— .i'^ u+!/ 



by which many of the resins may be represented. To this 

 subject I shall return in a future paper. 



Origin of the Mineral Resins. 



As I am not in possession of any other mineral substance 

 of organic origin exhibiting the characters of a resin, it may 

 not be improper here to advert to the probable origin of this 

 class of substances. 



1. Fossil Copal. — The composition of this substance clearly 

 indicates a vegetable origin. It has been found in small 

 quantities disseminated through the London clay. Under 

 what circumstances could this vast deposit of clay be formed ? 

 Most probably along the course, or in the estuary of some gi'eat 

 river, or in the bottom of a lake into which its waters were 

 poured. And if at this period the climate were warmer in these 

 latitudes than it now is, a circumstance in regard to which 

 geologists seem agreed, we should expect to find (recent) resins 

 similar to the fossil copal in similar localities, if any now exist 

 and under a similar sun. From what we know of theGuianas 

 stretching between the river Orinoco on the north and that 

 of the Amazons on the south, a country abounding in rivers 

 and lakes, liable to heavy rains and floods with a climate hot 

 and moist, we should suppose it to be not very unlike that 

 which poured its muddy rivers into the London basin, and 

 buried beneath its waters occasional fragments of its trees, its 

 resins, and its other vegetable productions. 



From the island of Cayenne on this coast, and probably 

 from the interior of French Guiana, is imported a resin the 

 produce of the locust tree, which like the Highgate resin has 

 much resemblance to copal, and is known in commerce by 

 the name of animc resin. This resin has been analysed by 



