92 



Prof. Johnston 07i the Cotnpositmi of certain 



Laurent, and found by bim to have a composition approach- 

 ing very nearly to that above given for the fossil copal. The 

 comparative results are as follows : 



Anime Resin. 



Carbon .. 

 Hydrogen 

 Oxygen 



84.-6 



11-5 



3-9 



100-0 



Fossil Copal. 

 1. 2. 



85-408 



11-787 



2-669 



99-S64 100 



85-677 

 11-476 



2-847 



From the above result he deduces for anime resin the 

 formula C^^ H33 O, which gives per cent. 



Carbon 85-66 



Hydrogen 11-538 



Oxygen 2-802 



100- 



The numbers given by this formula differ from those ob- 

 tained by Laurent in the oxygen and carbon to the amount of 

 one per cent., while they are almost identical with those given 

 by the analysis of the fossil copal. As the hydrogen however 

 is always in excess, the formula C40 Hg^ O above deduced from 

 my analysis is to be preferred. 



Without, however, dwelling upon this discrepancy, it is in- 

 teresting to find a resin still growing nearly if not absolutely 

 identical in constitution with one produced and buried at a 

 period so remote; and while this fact establishes the vegetable 

 origin of the fossil copal, it may be considered as throwing 

 some additional light on the nature of the climate at that re- 

 mote epoch and as confirming the evidence of other facts in 

 regard to the temperature of these latitudes during the depo- 

 sition of the London clay. 



2. Resin ofRetiiiasphalt * = Cg] H14 O3. 



The origin of this substance, found in the tertiary formation 

 of Bovey in Devonshire, of nearly the same age as the Lon- 

 don clay, is clearly indicated by the mode in which it occui's. 

 It is scattered throughout the deposits of lignite, and is pene- 

 trated by twigs and hollow quadrangular spines, apparently 

 the leaves of a coniferous tree. That it is the resin of some 

 such trees is therefore very probable; that it has flowed in a 

 liquid state is also probable from its being mixed with so 

 much clay, and it is not imlikely that it may have undergone 

 some change of composition since it was first deposited. We 

 know as yet however too little in regard to the composition 



* See Lond. and Edinb. Phil. Mag., vol. xii. p. 560. 



