238 Intelligence and Miscellaneous Articles. 



Tl* O* and RO^, R expressing the composition of a hypothetical 

 radical, margaryle, C^* H'^^*. 



On taking into consideration the great analogy of the physical 

 characters of these two acids and the perfect identity of their che- 

 mical properties, that is to say of their metamorphoses under the 

 influence of reagents, we were led to doubt the accuracy of the for- 

 mulae which established between them so great a difference. On 

 the other hand, the formula attributed to stearic acid was in contra- 

 diction to the propositions we have advanced respecting the divi- 

 sibility of the formulae of organic substances. Either these propo- 

 sitions were false or the composition of stearic acid adopted by 

 the Giessen school was inaccurate. Experiment could alone decide 

 this. Now we have found, in the first place, that stearic land mar- 

 garic acids have the same atomic weight; on this point we agree 

 with all those chemists who have analysed the salts. We have made 

 seven analyses of stearic acid, derived from four different sources. 

 The differences between the analyses amount for the carbon to one 

 or two-thousandths, and scarcely to one-thousandth for the hydrogen. 

 They lead exactly to the formula of margaric acid, viz. C^* H'^s O*. 

 We have likewise observed, as was announced by M. Chevreul long 

 since, that pure stearic acid may be distilled for the greater part 

 without alteration, and that it behaves in this respect like all the 

 other volatile acids of the same homologous series, as formic, acetic, 

 butyric acids, &c. If, under certain circumstances, this distillation 

 is accompanied by the formation of other products, for instance 

 liquid hydrocarbons, they may be entirely avoided by distilling from 

 15 to 20 grms. of the pure acid, and interrupting the operation as 

 soon as the last portions acquire a faint brownish tint. Again, if 

 some German chemists have observed in the distilled acid a lower 

 melting-point, which led them to view the product as margaric acid ; 

 this decomposition, if it occurs, is effected, according to us, without 

 any decomposition, and can only be the result of some molecular 

 change. 



In fact, a greater difference does not exist between stearic and 

 margaric acid than between tartaric and metatartaric acid ; they are 

 two physical varieties of one and the same chemical species ; mar- 

 garic acid should be called metastearic acid. 



This result is moreover confirmed by all the reactions known of 

 these bodies; the identit}' of composition and of characters of the 

 substances described by M. Bussy under the names of margarone 

 and stearone; the identity of the results obtained by M. Erdmann 

 in the analyses of the products of anhydrous phosphoric acid upon 

 stearic and margaric acids ; lastly, the identity of the atomic weights 

 of these two acids — all these facts now find their natural explanation 

 in this state of isomerism which we have pointed out. 



The chemical history of the fatty substances is thus simplified. 



* Margaric acid, C^^Hbso^+H^O ; stearic acid, 2(C3< H'^^) 05-f-2H2 (bibasic) 

 _Q68 H'-'^O^, with the oxygen indivisible by 2. 



