166 REPORT— 1900. 



exhibit continuous absorption, but show no absorption band, and, as was 

 to be expected, diketohexamethylene, in which the six carbon atoms are 

 united with each other by a single bond, as in hexachlorobenzene and 

 piperidine, likewise showed no bands in the spectrum. 



Thi-ough the kindness of Professor Sydney Young and Miss Fortey, 

 we have recently been enabled to examine a specimen of pure hexamethy- 

 lene prepared from Galician petroleum. This substance, in comparison 

 with benzene and pyridine, is highly diactinic. A layer, 60 mm. thick, 

 of a solution containing 1 mill.-mol. dissolved in 20 c.c. of alcohol, trans- 

 mits all rays up to ^ /\ 3920, whilst a layer of the same solution, 10 mm. 

 thick, transmits practically the whole spectrum. In none of the photo- 

 graphs of the spectra of this substance could any trace of a banded struc- 

 ture be detected. 



Tetrahydrohenzene. — Professor Young and Miss Fortey were also good 

 enough to place a specimen of pure tetrahydrobenzene in our hands for 

 examination. This substance exhibits somewhat greater general absorp- 

 tion than hexamethylene, a layer, 60 mm. thick, of a solution containing 

 1 mill.-mol. in 20 c.c. alcohol absorbing all rays beyond '/\ 3694, while 

 absorption is still traceable in a layer of the same solution 1 mm. thick. 

 Like hexamethylene, tetrahydrobenzene shows no selective absorption. 

 The examination of these two substances thus confirms the conclusion pre- 

 viously reached, that the banded spectrum is shown only by substances 

 which possess the true benzenoid structure.^ 



Ultra-violet Absorption Spectra of Albuminoids.'^ 



The first investigation of albuminoids of animal origin was made by 

 Soret : it included albumen, white of egg, pure albumen, caseine, and 

 serine. Absorption bands occur in their spectra in the following posi- 

 tions : — Albumen (white of egg) X 2880-2650, pure albumen X 2948- 

 2572, caseine A 2948-2572. Serine exhibits a band similar to that of 

 caseine. 



In addition to albumen the following substances have been examined -.'^ — 



(1) Gelatine ; (2) maize starch ; (3) cane sugar ; (4) glucose ; (5) yeast 

 water ; (6) invertase ; and (7) diastase. These are all highly diactinic 

 substances, considering their complex constitution, and they show no 

 absorption bands. It is evident, therefore, that the constitution of 

 albumen, caseine, and serine is very different from that of invertase, 

 diastase, gelatine, starch, glucose, and saccharose. 



This was of interest in connection with C. V. Naegeli's theory of 

 fermentation. Naegeli regarded fermentation as a process in which a 

 ti'ansference takes place to fermentable matter of the molecular or rather 

 intramolecular vibrations of the constituent substances entering into the 

 composition of living protoplasm whereby the equilibrium of the molecules 

 of the fermentable matter became so disturbed as to cause their resolution 

 into simpler molecules. It appears by no means improbable that the 

 diastatic ferments may have some such action. From this point of view 



' Hartley, Trans., 1881, 39, 1.53. 



- Comptes Rendiis, 97, p. 642 ; also Archives des Sciences Physiques vt Naturelleg, 

 X. p. 139. (L. Soret.) 



' Hartley, Tnms. Chcm. I'^oe., 1887. 51, 59. 



