xxii ruoCEEDINGS. \Mivrch lot/i, igi-^. 



Professor Edmund Knecht, Ph.D., read a paper by himself, 

 and Miss Eva Hibbkrt, Assoc. M.S.T., entitled, " On 1-pimaric 

 acid from French rosin." 



The authors have succeeded in preparing l-pimaric acid 

 from French rosin in considerable yield by the following 

 process : — The rosin is dissolved by heating over a free flame 

 with glacial acetic acid and the solution thus obtained is set 

 aside to crystallise. 'J'he semi-crystalline mass, which separates 

 after standing for periods varying from a week to a fortnight, is 

 filtered from the mother liquor and oily constituents on the 

 vacuum pump, and is purified by re-crystallising several times from 

 glacial acetic acid and then from methyl alcohol until the melting 

 point and optical rotation are constant. In this manner it is 

 possible to obtain a yield of the pure acid equal to about 12^ 

 per cent, of the weight of the rosin employed. 



Ultimate analyses and molecular weight determinations 

 showed that the product possesses the composition C^oHgoOo. Its 

 melting point is i6i°C. and its optical rotation a^=- - 80°. The 

 specific gravity at i5°C.was found to be i'o6. Exposed to the air it 

 is oxidised, this being accompanied by a yellowing of the crystals 

 and a drop in the melting point and optical rotation. Exposed 

 to oxygen in a fiask at a temperature of 8o°C., to constancy 

 the gas is taken up in the proportion of two atoms of oxygen 

 to one molecular weight of the acid. The methyl ether 

 C20H.19O2CH3 is a thick colourless liquid having an optical 

 rotation a^= - 53°. The tribromide C.joH.j7Br30o is obtained by 

 mixing in the cold solutions of bromine and of 1-pimaric acid 

 in petroleum spirit, and was shown to be a substitution and 

 not an addition compound; its optical activity is oij=25°. By 

 passing nitrous fumes into the solution of 1-pimaric acid in 

 petroleum spirit, the nitrosate C.oHaoO.jN-.Oj separates out as a 

 cystalline mass. 



When heated for several hours in an evacuated sealed tube 

 in the vapour of boiling aniline, 1-pimaric acid loses water and 

 yields an anhydride (CooH„90);0 which resembles rosin in 

 appearance and is optically inactive (in petroleum spirit solution). 



