Dr. R. D. Thomson on the Covodie Pine Resin. 85 



and the silver salt is 



Bidammarate of silver 2 (C^ Hgg 6 ) + AgO: 

 or supposing the hydrogen in excess, which is generally the 

 case with a resin unless it has been fused, the anhydrous acid 

 would be as follows : — 



Carbon . . 40 x *75 = 30- 75*4,7 



Hydrogen . 30 x *125 = 3- 75 9*43 



Oxygen . . 1x6* = 6* 15-09 



39-75 

 The difference between the hydrous and anhydrous acids 

 would then be one atom of water. 



Hydrous acid .... C 40 H 31 7 

 Anhydrous acid . . . O^ H m Q 6 



H O 

 Dammaran. 



I give this name to the substance remaining after the 

 separation of the dammaric acid. It is a fine white brittle 

 resin, apparently insoluble in weaker spirit, but forming with 

 absolute alcohol a beautiful colourless varnish, and also a si- 

 milar preparation with oil of turpentine. This substance is 

 identical in composition with the resin. When dried at 212° 

 its composition was as follows : — 



7*4 grs. burned with oxide of copper gave 20*36 C0 2 and 

 6-4 HO. 



This is equivalent to 



Carbon 75*02 



Hydrogen .... 9-60 



Oxygen 15-38 



100-00 

 This approaches closely 



C 40 H 3) 6 . 

 By exposing this substance to a higher and longer con- 

 tinued heat, it was found to absorb oxygen and to alter in its 

 composition, as appears by the following analyses : — 



I. 6*57 grs. gave 16-75 C0 2 and 5*7 HO. 

 II. 7*64 ... 20*33 C0 2 and 6*7 HO. 



I. II. 



Carbon .... 72-56 69*25 



Hydrogen ... 9*74 10'32 



Oxygen . . , . 17*70 20-43 



100- 100* 



The first specimen was dried at 300° for three days ; the 

 second at 350° for four days. 



