viii, a, 3 Pratt and Gibbs: Two Phthaloximes 185 



a weighed amount of silver salt in a porcelain boat. Decompo- 

 sition occurs with gradual loss of weight in a few hours. The 

 results of one experiment are as follows : 



Substance 

 (gram). 



Gain 

 (gram). 



Gain 

 (percent). 



0.2133 



0.0153 



6.81 





.0145 



6.80 





.0123 



5.76 





.0118 



5.58 



Calculated for 







CgH^NAg-NHs 





6.30 



The boat and contents were then heated at 100° with a loss 

 of weight corresponding approximately to the ammonia pre- 

 viously absorbed. The color remained a brownish gray, indi- 

 cating no recovery of the original silver salt. 



THE ACID SALTS OF PHTHALOXIME 



When an alcoholic solution of phthaloxime is treated with 

 alcoholic potassium acetate, an orange-colored crystalline salt 

 is precipitated. 24 A study of the absorption spectrum of this 

 double salt clearly showed that in solution it was identical with 

 the original oxime in the presence of one-half an equivalent of 

 potassium ethoxide. Sodium acetate forms a similar double salt 

 which is more difficult to crystallize and isolate. The underly- 

 ing reasons for this fact are to be found in the relative solubili- 

 ties of the normal sodium and potassium salts of phthaloxime. 

 We have found that 100 cubic centimeters of absolute alcohol 

 at 30° will dissolve 0.0590 gram of the potassium salt and only 

 0.0076 gram of the corresponding sodium salt. 



Since the absorption spectra of the double salts were found to 

 be identical with those of the oximes plus one-half an equivalent 

 of corresponding alkali, we concluded that these salts could be 

 crystallized from alcoholic solutions with equal ease by the addi- 

 tion of the proper amount of the hydroxide or ethoxide of the 

 metal. This was found to be the case, and the fact that sodium 

 or potassium acetate dissociates in solution, giving a small 

 excess of hydroxyl ions over hydrogen ions, explains why these 

 double salts were originally obtained by the addition of alkali 

 acetates, while the formation with alkali hydroxides was over- 

 looked. The double salts may also be prepared by mixing equal 

 molecular equivalents of alcohol solutions of oxime and the nor- 

 mal alkali salt and concentrating to crystallization. 



24 Orndorff and Pratt, loc. cit. 



