226 PROCEEDINGS OP THE AMERICAN ACADEMY. 



III. 0.3015 gram of the substance gave on combustion 0.2090 gram of 



carbonic dioxide and 0.0223 gram of water. 



IV. 0.1265 gram gave 0.2122 gram of argentic bromide. 

 V. 0.1279 gram gave 0.2147 gram of argentic bromide. 



VI. 0.1138 gram gave 0.1911 gram of argentic bromide. 

 VII. 0.1229 gram gave 0.2074 gram of argentic bromide. 



IV. V. Yi. vn. 



71.39 71.44 71.48 71.83 



Of these analyses I. and II. were of samples prepared and purified as 

 described ; III. to VII. were of specimens prepared earlier in our work, 

 and in some cases purified by slightly different, and perhaps less effective, 

 methods. 



Two determinations of the molecular weight were made by the method 

 of freezing, the solvent being benzol. 



I. 0.262 gram of the substance dissolved in 16.58 grams of benzol 



produced a depression of 0.099°. 



II. 0.594 gram of the substance in 16.58 grams of benzol produced a 



depression of 0.219°. 



I. II. 



Molecular Weight 782 802 



o* 



The most probable formula to be derived from these data is CuIIoBrgOs, 

 formed by the union of two molecules of tetrabromorthoquinone with one 

 of acetic acid, one molecule of water being eliminated. The results, 

 however, agree almost as well with Ci4Brg06, although the percentage of 

 hydrogen found is high for a substance which is free from this element. 

 A compound with the formula C^BrgOs would be formed by the removal 

 of two atoms of hydrogen from the preceding compound, a reaction which 

 might easily be brought about by the oxidizing action of a portion of the 

 tetrabromorthoquinone ; the tetrabrompyrocatechine thus formed in turn 

 acting on the unaltered quinone would give the red body which, as 

 already stated, is always produced with the white substance ; but it 

 should be remembered that the quantity of the red body formed is far 

 below that which would be expected from such a reaction. 



