172 The Philippine Journal of Science wis 



if a salt is formed it must have the true oxime structure. The 

 addition of increasing amounts of water to the pyridine solution 

 causes a progressive deepening of color and gradual production of 

 a color band until the characteristic red of the alkali salts is 

 obtained. This effect is explained by the increased basicity of 

 the pyridine hydrate formed upon the addition of water. The 

 salt is unstable, and could not be isolated from solution without 

 the entire loss of pyridine. 



The silver salt of phthaloxime is insoluble in the ordinary 

 solvents, and its true absorption spectrum could not be obtained. 

 It dissolves readily in pyridine with a purplish red color, prob- 

 ably due to the formation of an addition product containing the 

 strongly positive silver dipyridine. A similar product was iso- 

 lated in the case of ammonia where one molecule of crystalline 

 silver salt was combined with one molecule of ammonia. These 

 addition products are deeply colored as might be expected from 

 the strength of the double base. That the absorption band of 

 their spectra heads at a different place than that characteristic 

 of the alkali oxime salts is probably due to the presence of addi- 

 tional latent valencies in the unsaturated nitrogen atom of the 

 pyridine-silver or ammonia-silver groups. 



It is evident that the introduction of various positive atoms 

 or radicals into the phthaloxime molecule may cause different 

 changes in its optical activity. It may be assumed that the pre- 

 vious condition of equilibrium existing between the unsaturated 

 =CO and =NOH groups is completely changed, and that the 

 latent valencies of these groups no longer mutually neutralize 

 each other, but that a negative portion swings to the positive 

 metal. The equilibrium will be slightly different in various salts 

 depending upon the electropositiveness of the substituting atom 

 or group, but will always be of the same type unless further 

 complicated by the introduction of other unsaturated atoms. 

 The result of the new equilibrium between the positive group or 

 atom and the negative partial valency of an unsaturated atom is 

 shown by the disappearance to a greater or less extent of the 

 absorption spectrum characteristic of the original type and the 

 production of a new band in the spectrum. 



The position of the new band and consequent color, in the broad 

 sense, of the salt given by any compound undergoing changes of 

 this general type will depend upon the resulting configuration 

 of the molecule. The presence of the benzene ring or its equiv- 

 alent in the molecule is probably essential whenever the absorp- 

 tion band of the salt falls in the characteristic quinone position. 



