1G2 REPORT— 1900. 



toxime containing 1 niilligram-mol. in 20 c.c. shows a continuous spectrum 

 to ^/\ 388G (\ 2573) ; a layer 1 mm. thick of the same solution to 

 '//\ 4125 (\ 2424). 



The substances above referred to aflford an excellent illustration of 

 the intimate relation between the character and extent of absorption 

 and the constitution of an organic compound. Ammonia is highly 

 diactinic. The substitution of a methyl group for one of the hydrogen 

 atoms has the effect merely of very slightly increasing the amount of 

 continuous absorption of the most refrangible rays. Again, the sub- 

 stitution of hydroxyl for hydrogen has a similar effect, the group OH, 

 however, haviiig a greater absorptive power than the group CH3, 

 When we come to acetaldoxime and acetoxime, we find that, regarding 

 them as derivatives of hydroxylamine, the introduction of the more 

 complicated groups -.CH'CHa and :C(CH3)2 respectively for the two 

 remaining hydrogen atoms of the original ammoiiia molecule, is 

 accompanied by a great increase in the amount of the general absorption. 

 Comparing, liowever, acetaldoxime with acetoxime, the latter, which 

 differs from the former in tlie possession of an additional methyl group, 

 shows only slightly greater absorption. This is in harmony with previous 

 observations on COgH groups, and the slightly increased absorption 

 caused by the introduction of methyl groups for hydrogen atoms ; also the 

 stronger absorption caused by the replacement of hydrogen atoms by 

 hydroxyl radicles. 



A diagram drawn to a scale of oscillation frequencies shows at a 

 glance the length of spectrum transmitted by these substances in different 

 proportions, and through different thicknesses. 



The Curves of the Molecular Vibrations 0/ Benz&ntialdoxime 

 and Benzsynaldoxime.^ 



Benzantialdoxime and henzsynsildoxime are now generally represented 

 by the following formulae : 



C6H5"C'H C(^Hr^'C'lJ. 



II ' II 



OHN . NOH 



Benzaw^mldoxime. Benzs?/7ialdoxime. 



If these formulae correctly represent the constitution of the two forms of 

 benzaldoxime and their relation to one another, we should expect both 

 compounds, as stereo-isomerides, to exhibit the same character and 

 amount of absorption. As a matter of fact, we have found that the 

 curves of the molecular vibi'ations of the two substances in ethereal 

 solution are identical. A layer 25 mm. thick of a solution of either form 

 of the aldoxime containing 1 milligram-mol. dissolved in 100 c. c. of abso- 

 lute ether, absorbs all rays to ^/X 3323 {\ 3009). A layer 1 mm. thick of 

 a solution containing 1 milligram-mol. in 500 c.c. of ether transmits all 

 rays to ^ /\ 3638 (X 2748), and shows an absorption band reaching from 

 VX 3638 (X 2748) to '/^ 4321 (X 2314). This band is still distinctly 

 traceable in a layer 1 mm. thick of a solution containing 1 milligram-mol. 

 in 2500 c.c. of ether. 



' Hartley and Dobbicj^TVaws; Chen. Soc.,yo\, Ixsvii. 



