182 The Philippine Journal of Science wis 



THE ABSORPTION SPECTRA OF PHTHALOXIME SALTS IN 90 PER CENT 



ALCOHOL 



Weighed quantities of the pure salts were dissolved in the 

 requisite volume of water and absolute alcohol added at once 

 to make a 90 per cent alcohol solvent. In this manner exactly 

 1 equivalent of alkali to 1 of oxime was easily obtained. Photo- 

 graphs were made on Cramer's spectrum plates to cover as much 

 of the color absorption band as possible, and the curves in fig. 3 

 plotted from these. 



Description of fig. 3. — The curves show that the ammonium, 

 barium, sodium, and potassium salts give absorption bands head- 

 ing at T = 2300 in each case, but appearing at increasing dilu- 



1 

 tions. The original ultra-violet oxime band heading at -r = 3400 



was most pronounced in the ammonium salt and least in the po- 

 tassium. The barium and sodium salts give intermediate curves. 

 The residual oxime band gives an indication of the relative dis- 

 sociation of the different salts, and corresponds in persistence 

 inversely with the strength of the base. The silver salt of 

 phthaloxime in crystalline form shows a deeper red than the 

 corresponding potassium salt, but could not be included in the 

 series because of its insolubility. 



THE ABSORPTION SPECTRA OF PHTHALOXIME AND ITS SALTS IN 



PYRIDINE 



Pyridine is the only suitable solvent for the silver salt, and 

 gives a deep purplish red solution containing an addition product 

 of salt and base. 



Description of fig. k. — The absorption band appears at greater 



dilution, and heads at t- = 2140. It is of the same general type 



as the corresponding band given by the alkali salts, but shows 

 by its position farther toward the red that a slightly different 

 molecular equilibrium is represented in the compound. The 

 curve given by oxime in pyridine shows general absorption ex- 

 tending into the visible spectrum, but retaining the oxime type. 

 It is probable that no true salt is formed since a weighed amount 

 of oxime did not gain in weight when dry pyridine vapor was 

 passed over it. The dash curve represents oxime dissolved in a 

 mixture containing equal volumes of water and pyridine. The 

 color of this solution is deep red, and the absorption spectrum 

 clearly shows the presence of a true salt. 



