and the Theory of Chemical Types. 445 



Now let us go further : let us suppose that the marsh gas 

 be subjected to the action of chlorine ; very different actions 

 might be produced, if we only consult the general forces of 

 chemistry. 



Viewed precisely by the theory of organic types, if the 

 marsh gas corresponds to chloroform, to methylic tether, &c., 

 it realizes the carburet of hydrogen, which constitutes the 

 starting point of this series, and by means of chlorine it should 

 give : 



CVfl \ hydrochlorate of methylene, 

 p, 4 > monochloridated hydrochlorate. 



p, g > chloroform. 



C'* Ch® chloride of carbon. 

 We know, by the experiments which I recently made known 

 to the Academy, that marsh gas obtained from the acetates 

 changes under the influence of chlorine into this chloride of 

 carbon C"* Ch^ which the theory of types had predicted as the 

 necessai'y product of the action. 



Let me add too, that before giving this chloride of carbon, 

 it also produces some chloroform. But if marsh gas [gas des 

 ma7'ais) corresponds to the chloroform as the acetic acid does 

 to chloracetic acid, the conversion of marsh gas into chloro- 

 form is as necessary a fact as the conversion of the acetic 

 acid into marsh gas. 



If when these necessary facts have been recognized as true 

 be experience, it be then proved that they were possible, that 

 they did not disagree with the general laws of chemistry, I 

 contend that the difficulty has not been met. What ought to 

 be done in such a case, is to show how the general theory 

 allows us to foresee that acetic acid should give marsh gas, 

 and that marsh gas should give chloroform. 



Far from thinking that I have gone too far in establishing, 

 as I have done, genera for uniting acetic acid and chloracetic 

 acid, marsh gas, and chloroform, I have on the contrary been 

 too cautious. 



I therefore persist in my opinion as to the propriety of 

 uniting into one genus those bodies isohich contain the same 

 number of equivalents united in the same manner, and isohich are 

 endowed with the same fundamental chemical jiroperties. 



In this discussion of the characters of chemical types and 

 of the true acceptation of the fundamental properties of 

 bodies, I have said nothing of the identical function attributed 



