128 Mr. H. Caro on the Formation of 



acetic acids were heated at 120° C, two products were formed, 

 one possessing all the properties of rosolic acid (while the 

 other had the character of brunolic acid)." They like- 

 wise found "that a mixture of iodine and carbolic acid, when 

 heated with formic, acetic, butyric, and valerianic acids, produce 

 rosolic acid or a similar substance. A mixture of iodine and 

 carbolic acid did not give a similar result (but a black solid, con- 

 taining iodine)." 



In an analogous manner rosolates are formed by heating mo- 

 nobromophenylic acid with alcholic potash*. 



The most interesting formation of rosolic acid, and that which 

 has led to the practical application of this colouring-matter upon 

 a large scale, was discovered by Kolbe and Schmitt during their 

 researches upon the synthetical formation of salicylic acid from 

 phenylic alcohol. In a paper " On a Red Colouring-matter from 

 Creosote "t, Kolbe and Schmitt give a detailed account of the 

 formation and properties of a red colouring-matter which is pro- 

 duced by digesting at 140°-150° C, a mixture of 1 part oxalic 

 acid, 1 J part " colourless commercial creosote," and 2 parts con- 

 centrated sulphuric acid. The resulting product appeared to the 

 authors " to be closely related to, if not identical with, Runge's 

 rosolic acid" || . 



This beautiful reaction was first applied commercially by 

 Messrs. Guynon, Marnas, and Bonnet, of Lyons, for the manu- 

 facture of rosolic acid, which was converted into the remarkable 

 red (pseonine, coralline rouge) and blue (azuline) by the action of 

 ammonia and of aniline respectively §. The introduction of 

 these dyes promoted the manufacture of carbolic acid, which in 

 this country, mainly by the endeavours of Prof. F. C. Calvert 

 and Mr. Charles Lowe of Manchester, has now arrived at a high 

 state of perfection. 



It will be observed that in the foregoing researches there is 

 little or no indication of the degree of purity of the phenol em- 

 ployed by the different experimenters. I have proposed to my- 

 self to answer the following queries : — 



1. Whether, the agent being simply an oxidizing one, it is 

 necessary to have cressylic alcohol as well as phenol ? 



* Korner, Ann. der Chem. und Pharm. vol> xxxvii. p. 203. 

 t Ann, der Chem. und Pharm. 1861, vol. cxix. p. 169. 



Calculated for the formula 



€ 20 H 16 O 3 , H 2 



(Wanklyn and Caro). 



74-54 



5-59 



19-87 



10000 



% Runge's rosolic acid 



(H. Miiller). 

 C .... 7561 

 H .... 5-78 

 O .... 1861 



[Kolbe and 



Schmitt. 



74-85 



5-15 



20-00 



100-00 

 § Rtpert, de Chim. Appl. 1862. 



10000 



