440 Noiices of the Labours of Coniinenial Chemists. 



filter. The resin remains on the filter, and a solution of ben- 

 zoic acid passes through. The benzoin is boiled two or three 

 times, as stated above, and then treated with aether, which 

 dissolves half of it; on evaporation the aether deposits a 

 resin. The third resin which remains behind is soluble in 

 alcohol. This latter is Berzelius's betaresin, that soluble 

 in aether the alpharesin, and the third gammarssin ; these 

 resins thus prepared are not perfectly jnire. The gamma- 

 resin must be boiled with water to free it from benzoic acid, 

 it then melts at 180° C, and is pure. The alpharesin forms 

 an insoluble compound with carbonate of soda; by long boil- 

 ing of the benzoin with carbonate of potash, all alpharesin is 

 extracted, for it is converted into gammaresin and becomes 

 soluble. Carbonate of soda effects this change very slowly. 

 After the extraction of the alpharesin by H?ther, there remain 

 behind betaresin, the alpharesin compound and the impurities ; 

 these latter remain when the mass is boiled with alcohol; 

 on cooling the alpharesin compound is precipitated ; the be- 

 taresin remains dissolved. The properties of these resins have 

 been described by Unverdorben, Poggendorff's An?ialen, xvii., 

 Berzelius's Chemic, vii. 



The formula for the alpharesin is C"" H"' O'^; the atomic 

 weight, as found from the analysis of the lead compound, is 

 7214-'20; calculated 7274-58. Betaresin is C^°H"0'; the 

 analysis of the lead salt gives, as atomic weight, 4099'9; cal- 

 culated 4231 'Dl. 



Gammaresin isC'°H*°0'; atomic weight 3042*64'; accord- 

 ing to analysis 3062"81. It is probable, from what has been 

 said above concerning the metamorphosis of alpharesin into 

 gammaresin, that benzoin contains only two resins for 



Alpharesin C"" + H*^" + O'* 



viinus Gammaresin C" + H'" + O' 



Betaresin C^" + H" + O ' 



They may be considered as oxides of C* H* combined with 

 a hydrocarbon ; thus 



Alpharesin .... 14 (C* H^) O^ + 14 CH- 



Betaresin 9 (O H') O' + 4CH'- 



Gammaresin... 5 (O H^) O^ +10CH" 



{Avnalen dc7- Pharmacie, xxxiv.) 

 [The account of Mr. Johnston's experiments, Phil. Mag. 

 vol. xvii. p. 384, is too short to allow of any conclusions being 

 drawn from it. 1 am not acquainted with the methods Mr. J. 

 used for purifying his resins. It appears, however, tiiat he has 

 not observed the alpharesin of Van der Vliet. In paragraph 4, 



