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XII. Intelligence and Miscellaneous Articles, 



LETTER TO PROF. LIEBIG ON THE THEORY OF SUBSTITU- 

 TIONS*. 



Sir, 

 T HASTEN to communicate to you one of the most brilliant facts 

 *- of organic chemistry. I have verified the theory of substitutions 

 in an extremely remarkable and perfectly unexpected manner. It is 

 only from the present time that we shall be able to appreciate the 

 high value of this ingenious theory, and to foresee the immense dis- 

 coveries it projmises to realize. The discovery of chloracetic acid, 

 and the constancy of the types in the chlorinated (chlores) compounds 

 derived from aether and the chloride of sethyle, have led me to ex- 

 periments which I will now describe. I passed a current of chlo- 

 rine through a solution of the acetate of manganese under the direct 

 influence of solar light. After twenty-four hours I found in the 

 liquid a superb crystallization of a yellow violet salt. The solution 

 contained nothing further than this salt and hydrochloric acid. I 

 analysed this salt : it was the chloracetate of the protoxide of man- 

 ganese. Nothing extraordinary as yet ; a simple substitution of the 

 hydrogen of the acetic acid by an equal number of equivalents of 

 chlorine, already known from the beautiful experiments on chlora- 

 cetic acid. This salt, heated to 110° in a current of dry chlorine, 

 was converted with disengagement of oxygen into a new compound 

 of a gold yellow colour, the analysis of which had for its composi- 

 tion to the formula Mn CI 2 + C4 CI 6 O 3. There was therefore a 

 substitution of the oxygen of the base by chlorine, similar to what 

 has been observed in a multitude of cases. The new substance 

 dissolved in quite pure chloral with the aid of heat. I employed 

 this liquid, unalterable by chlorine, in order to continue the treat- 

 ment by means of this agent. I passed dry chlorine during four 

 days, keeping the liquid constantly near its boiling point. During 

 this time a white substance was constantly deposited, which, when 

 attentively examined, proved to be the chloride of protochloride (?) of 

 manganese. I cooled the liquor when all precipitation had ceased, 

 and obtained a third body in small needles, silky and of greenish yel- 

 low colour ; it was C 4 CI 10 O 3, or in other terms it was the acetate 

 of manganese, in which all the hydrogen and the oxide of manga- 

 nese had been replaced by chlorine. Its formula should be written 

 CI 2 CI 2 + C 4 CI 6 3. There were therefore six atoms of chlo- 

 rine in the acid, the four other atoms representing the oxide of 

 manganese. Just as hydrogen, so also manganese and oxygen may 

 be replaced by chlorine, and nothing surprising will be found in 

 this substitution. But this was not the end of this remarkable 

 series of substitutions. On letting a new chlorine act on a solution 

 of this substance in water, there was a disengagement of carbonic 

 acid ; and on cooling the liquid to + 2°, a yellowish mass, formed of 

 small laminse, was deposited, very much resembling the hydrate of 



* From Liebig's Journal der Chemie und Pharmacie, vol. xxxiii. part 3. 



