(51) 
embryos more than 2 dm. long, preserved in xylol. These preparations 
were exceedingly beautiful at first and the non-cartilaginous tissues 
transparent, as clear as crystal; later on however they lost the 
transparency for the greater part and became opalescent. The cause 
of this change is unknown to me. Such macroscopic preparations 
ought therefore also to be enclosed in canada-balsam or dammar-resin. 
Chemistry. — “J/ntramolecular rearrangement of atoms in azory- 
benzene and its derivatives.” By Dr. H. M. Kyrescuner. (Com- 
municated by Prof. LoBry pr Bruyn.) 
Watiach and Beru *) noticed a long time ago that azoxybenzene 
is converted into its isomer p-azoxybenzene by gently heating it with 
sulphuric acid, or by means of fuming sulphuric acid at the ordinary 
temperature. BAMBERGER found that in this process there is also formed 
half a percent of o-oxyazobenzene a substance discovered by him 
some time ago when acting on nitrosobenzene with aqueous caustic 
soda at 100°. The reaction noticed by Warract and Berrr must be 
represented as follows : 
N—N 
REN 
Sulphuric acid was up to the present the only reagent capable of 
C,H C,H, > C,H, N—=NC, H, OH (1.2 and 1.4). 
causing the said intramolecular rearrangement of atoms. W ACKER ®), 
however, when stating in his paper on «-azoxynaphtalene that this 
substance turns red by exposure to direct sunlight, also remarks that 
azoxybenzene is likewise sensitive to sunlight, but he only mentions 
that it turns deep yellow without having investigated the nature of 
the change. 
Various derivatives of azoxybenzene also appeared to be liable to 
the same intramolecular rearrangement of atoms, but again sulphurie 
acid is mentioned as the only reagent capable of causing the change. 
The result of those investigations showed that some of the substitution 
products, namely the meta-derivatives, are almost quantitatively con- 
verted into the isomeric phenols, while the ortho- and para-derivatives 
are only affected to a small extent or not at all. 
1) Ber. 13. 525 (1880). 
2) Ber. 38, 3192 (1900). 
5) Ber. 33. 1939 (1900). 
4) Ann. 31%. 313 (1901). N 
4* 
