32 Mr. Noad on the Action of Nitric Acid on Cymol. 



luylic acids have established the composition of these two 

 compounds in a perfectly satisfactory manner, there still re- 

 mained one experiment to be made in order to prove that 

 toluylic acid occupies in the toluyle series the same place which 

 benzoic acid has in the benzoyle series ; in order to prove 

 that the acids analysed are really the true toluylic and nitro- 

 toluylic acids, and not merely bodies having the same com- 

 position, being isomeric with them : this experiment was to 

 attempt the transformation of toluylic acid into toluol under 

 the same circumstances by which benzoic acid becomes con- 

 verted into benzol. I devoted the acid from four ounces of 

 cymol to this experiment, and by distillation with caustic 

 baryta, which I found to answer much better than lime, I 

 obtained some grammes of a beautiful limpid coloui'less liquid, 

 having the precise smell of the carbo-hydrogen sought for. 

 By distillation from a fresh portion of baryta the oil was ren- 

 dered perfectly anhydrous ; in this state its boiUng-point was 

 taken. It began to boil at 109°, the thermometer gradually 

 rose to 110°-5, barometer O'^^CS (30-1 inches). 



It was burned in the ordinary manner with oxide of cop- 

 per and yielded the following results : — 



0-2410 grm. gave 0'809 grm. of carbonic acid and 0'19G 

 grm. of water, corresponding in per cents, to 



Carbon . . . . 91-50 

 Hydrogen . . . 9*03 



and agreeing exactly with the formula of toluol, Cj4 Hg, as the 

 following comparison shows : — 



Theory. Experiment. 



I « I 



14 eqs. Carbon ... 84 91-3 91-50 



8 ... Hydrogen . . _8 _%'1 903 



22 100-0 100-53 



The formation of toluol from toluylic acid is perfectly ana- 

 logous to the production of benzol from benzoic acid. 



C,6 Hg O4 + 2BaO = C,4 Hs + 2^BaO, CO^). 



Toluylic acid. Toluol. 



The remainder of the carbo-hydrogen was converted into 

 nitrotoluol by the action of fuming nitric acid: the well- 

 washed oily fluid was then dissolved in alcohol, saturated with 

 ammoniacal gas and treated repeatedly with sulphuretted 

 hydrogen, the whole being distilled after each saturation with 

 hydrosulphuric acid, to facilitate the deposition of the sul- 

 phur ; the dark red solution was evaporated to expel the al- 

 cohol, water added, and then submitted to distillation with 



