1885.] The Chemical Constitution of Isatin. 193 



to leave the nucleus of the compound unchanged, must be expected to 

 exhibit absorption-bands. 



It dow appears highly probable — 



1. That morphia and some other of the opium bases are derived 

 from pyridine. 



2. That strychnine is a derivative of pyridine. 



3. That brucine is a derivative of tetra-hydroquinoline, or an addi- 

 tion-product of quinoline of the same character, since there is a 

 remarkable similarity between the absorption curves of the two first- 

 named substances. 



I cannot close this paper without acknowledging indebtedness to 

 the great skill and care that my assistant, Mr. W. R. Barnett, has 

 bestowed on these later observations. 



II. " Contributions towards the Solution of the Chemical Con- 

 stitution of Isatin." By H. Kolbe. 



[The following pages contain the last experimental researches — 

 unfortunately unfinished — of Hermann Kolbe, upon isatoic acid (Isato- 

 saure) and its transformations. I have endeavoured, in drawing up 

 this paper, to infuse into it the true meaning and spirit of the 

 deceased. This difficult task has been made all the lighter for me 

 from my having had, at the time these investigations were being 

 carried out, frequent conversations with him upon the subject of them,, 

 but especially by his own exact notes. Dr. Th. Bellmann and Herr 

 Gr. Schmidt, who assisted Professor Kolbe in part of the researches 

 herein described, have also given me valuable assistance. 



The title of this paper, " Contributions towards the Solution of 

 the Chemical Constitution of Isatin," is from the author himself. He 

 began to write the paper but a few hours before his death. The 

 opening paragraphs (printed in italics) are the last bequest which he 

 has made to us. The concluding ones (also in italics) are taken from 

 remarks made by him which were plainly meant to form a part of this 

 communication. 



E. v. MEYER.] 



Notwithstanding that so many facts have been collected with the object 

 of definitely settling the constitution of isatin, yet arguments of iveight 

 sufficient to support a hypothesis of its rational constitution, or indeed to 

 raise it above the mere level of a hypothesis, are still wanting. 



The property of isatin of forming crystalline compounds with the alka- 

 line bisulphites led to the supposition of its belonging to the class of alde- 

 hydes or ketones; its property, when in contact with bases, of assimilating 

 the elements of water, and therewith forming isaiic acid, from which 



