390 



determination of the silver salt, showed it to be identical with the pre\-io\is acid. 

 Both portions were then mixed and purified together. The amount of this acid 

 (Dundathic acid^ in the resin of Agathis robusta is thus i6 per cent. It was purified 

 by twice repeating the precipitation from alcohol with solid potash, then finally 

 dissolved in absolute alcohol, adding a few drops of water and crystallising out. 

 The first portion precipitating was remo\'ed, as it contained a small amount of ash, 

 and the crystallisation from alcohol was repeated four times. It was finally dried 

 on a porous plate and heated at 100-105° C. The acid was a colourless powder, and 

 melted at 234-235° C. to a yellow resin. It was dextro-rotator}-, and 0-4 gram 

 dissolved in 10 c.c. absolute alcohol had a rotation in loo-mm. tube 4- 2-25°, thus 

 the specific rotation was [(?]„ 4- 56-25°. 



It was practically insoluble in chloroform and ether, but soluble in alcohol, 

 acetone, and ethyl acetate. A portion in chloroform did not dissolve on the addi- 

 tion of acetic anh}'dride in the cold, but did so on boiling, ^^'hen cold, one drop 

 of sulphuric acid to this solution gave a yery slight pink colouration, which on 

 standing eventually changed to a brownish tint. 



0-1516 gram dissolved in alcohol required 4-5 c.c. decinormal XaOH to 

 neutralise it, so that 40 grams NaOH would neutrahse 336 grams acid. 



0-1547 gram required 4-65 c.c. decinormal soda, or 40 grams NaOH would 

 neutralise 333 grams acid. 



Analysis gave the following results : — 



0-1516 gram gave 0-419 gram COo, and 0-1342 gram HoO. 



C- = 75' 3^; H. = 9-83 per cent. 

 0-1258 gram gave 0-3478 gram CO.,, and o-iiig gram HoO. 



C. = 75"4i ; H. = 9-88 per cent. 

 CjHkOs requires 75*84 per cent. C, and 97 per cent. H. 



The silver salt was prepared in the usual way from two distinct portions 

 of acid, and the following results were obtained : — 



0"i642 gram silver salt gave 0'040i gram silver — 2442 per cent. Ag. 

 0'i6io gram silver salt gave 00394 gram silver = 24-47 P^'" cent. Ag. 

 CjiHgiAgOs contains 24-6 per cent, silver. 



From the molecular determinations and the titrations, supported by tlie 

 results of the analyses, the formula C.^Yisf^s appears to be the correct one for 

 this acid, especially as corresponding results were obtained with tlic same acid 

 isolated from the resin of Araucaria Cunninghamii 



The acid of low-melting point, of which the bulk of the resin consisted, 

 was soluble in an excess of alcoholic potash. The alcoholic solution was removed 

 from the pasty acid salt, water added and boiled to expel all the alcohol. 

 When cold, water was added until the solution was quite clear, acidified with 



