M. Pasteur on Aspartic and Malic Acids. 285 



has been conducted with the same conjunction of acquaintance 

 with different branches of science and experimental methods as 

 the former. The only difference is, that in this instance a cir- 

 cumstance which had not been foreseen furnished him with the 

 principal subject matter ; so that it might be said that it was 

 met with by chance, if indeed the name of chance may be ap- 

 plied to the following out of a phsenomenon recently announced 

 as an isolated fact, of which a mind prepared to receive it at 

 once recognises its important relation to his previous investiga- 

 tions, and developes the general consequences which result from 

 it. The circumstances which have led to that development in 

 this particular instance are worthy of being recalled, for they 

 clearly confirm the thesis which we have endeavoured to establish 

 at the commencement of this report. 



Last year M. Pasteur made his researches upon asparagine, 

 aspartic acid and malic acid. These two acids ai'e theoretically 

 and practically derived from asparagine, by taking fi'om it one 

 or two equivalents of ammonia. It was precisely for this reason 

 that he selected these three bodies as the subjects of his study. 

 The molecule of asparagine possesses the power of rotation. He 

 wished to ascertain if that power was preserved after the pro- 

 gressive abstraction of the elements of ammonia ; and if such was 

 the case, what modifications it underwent. Experiment proved 

 that it was retained, and that it ceased only when the transition 

 from malic acid to those pyrogenous acids called maleic and para- 

 maleic took place ; the latter of which is also called fumaric acid, 

 in consequence of its being met with in the common fumitory. 

 This brief resume is sufficient for our purpose. Whilst M. Pas- 

 teur presented his memoir to the Academy, M. Dessaignes of 

 Vendome announced that he had succeeded in preparing aspartic 

 acid artificially by acting upon the acid fumarate of ammonia by 

 a process which he described*. 



This announcement immediately presented to M. Pasteur an 

 alternative, the experimental examination of which could not 

 fail to lead to an important discovery, — either that the aspartic 



* IVI. Dessaignes had previously obtained artificial aspartic acid by acting 

 upon the bimalate of ammonia. He communicated this fact in a note 

 wnieh was presented to the Academy at the seance of the 18th of 

 March 1850, and which is inserted in the Cnmptes Rendus, vol. xxx. p. 324. 

 But in a subsequent note, also presented to the Academy upon the 18th of 

 September in the same year, and inserted in the Comptes Rendus, vol. xxxi. 

 p. 432, M. Dessaignes added, that he hud rejiroduced the same artificial 

 aspartic acid as a derivative of malatc and fumarate of ammonia by the same 

 process. This second announcement surprised M. Pasteur, because these two 

 salts, which are designated as generators, do not possess any rotatory power. 

 lie has, moreover, established the fact by numerous repetitions of the ex- 

 periment, that the second mode of derivation indicated by M. Dessaignes 

 18 not less accurate than the former, and virtually leads to the same result. 



