392 



o-S gram acid was dissolved in lo c.c. semi-normal alcoholic potash, water 

 added and titrated. The excess of alkali requires 4-7 c.c. semi-normal sulphuric 

 acid to neutralise it ; therefore 56 grams KOH would neutralise 303 grams acid. 



Analyses gave the following results : — 

 0"i475 gram gave 0-4008 gram CO,,, and 0-1279 gram H.,0. 



C. = 74-2; H. = 9-63 per cent. 

 0-1492 gram gave 0-4097 gram COo, and 0-1281 gram H,0. 



C. = 74-88; H. = 9-54 per cent. 

 CjoHisOs requires 74-94 per cent. C, and 9-28 per cent. H. 



The silver salt was prepared in the usual wa}-, and this gave the following 

 results : — 



0-2236 gram silver salt gave 0-0592 gram silver = 26-47 per cent. Ag. 

 0-1691 gram silver salt gave 0-0454 gram silver = 26-84 per cent. Ag. 

 C,,,Ho7AgO:j contains 26-28 per cent, silver. 



From the molecular determinations, titration results, and the analj'ses, 

 the formula Ci;,H.^,0:. is indicated for the acid of low-melting point occurring in 

 the resin of Agathis robiista. 



That the above two acids were alone present in the resin was indicated 

 by the results obtained with the acid of low-melting point, when this was first 

 separated from the other acid, and before the final purification with aqueous soda. 

 The titration result indicated one acid with a molecular weight 302, and the silver 

 salt gave 26-4 per cent, silver. 



Ether Extr.act from the Resin Acids. 



The ether solution from the 25 grams of resin, after the acids had been 

 removed, was evaporated to dryness, and heated on the water bath till constant. 

 The residue weighed 2-7 grams, equal to 10-8 per cent. It was a soft, slight])' 

 yellow resinous mass, had a somewhat aromatic odour and a \ery bitter taste. 

 It was dissolved in alcohol, and made up to 30 c.c. ; the solution was dextro-rotatory 

 to the extent of 4- 3-2° in loo-mm. lube ; the specific rotation was thus [rf]„ 

 4- 35-6°. It thus agrees in rotation with tlie acid of low-iuelting point. 



To the solution a small amount of water was added and evaporated in thr 

 air, and although the neutral resinous bodies appeared to be quite amorj)hous, 

 yet a few, somewhat long needle crystals could be detected in the thinner 

 portions. Under the microscope these were seen to be terminated ])risms, and 

 they were soluble in water, and the aqueous solution had an intensely bitter 

 ta.ste; on evaporating, microscopic crystals were again formed. This crystalhnc 

 substance is apparently the bitter principle occurring in these resins, and may, 

 perhaps, be isolated in tliis manner. 



