Mr. Noad on the Action 0/ Nitric Acid on Cymol. 21 



of the corresponding salt of the nitrogenous acid in the same 

 menstruum. The crude acid is thrown on a filter, and the 

 adhering nitric acid removed by washing with cold water ; it 

 is then boiled with hydrate of lime, and the resulting lime- 

 salt, filtered when quite cold, afterwards decomposed by nitric 

 or hydrochloric acid; if the acid does not precipitate tolerably 

 Mhite, the same operation is repeated, and the well-washed 

 acid is then dissolved in baryta water and carefully evaporated 

 to dryness on the water-bath ; it is redissolved in cold water, 

 filtered, reprecipitated by hydrochloric acid, washed, and the 

 process repeated until the dry baryta salt dissolves completely 

 in cold water ; it should then be once or twice crystallized, 

 after which it is generally (juite pure. 



The quantity of pure acid as thus obtained from 2 oz. of 

 cymol is very small, but I have not hitherto been fortunate 

 enough to discover a better or less circuitous method of pro- 

 curing it ; could an oxidizing action be effected on the oil 

 Avithout the use of nitric acid a great saving would undoubt- 

 edly be achieved, but, as before stated, all my attempts in 

 this direction proved unavaihng; it is not impossible that the 

 object may be obtained by permanganate of potash. I made 

 one experiment with this salt, and there was evidently a re- 

 duction of the permanganic acid, but no trace of toluylic acid 

 could be discovered, from which it seems evident that the 

 oxidation had in this case proceeded too far and the cymol 

 become converted into carbonic acid ; this reaction has not 

 however as yet been sufficiently studied. 



Composition of Toluylic Acid. 



On submitting toluylic acid to elementary analj-sis in the 

 usual manner, by burning it with oxide of copper, I obtained 

 the following results : — 



I. Acid obtained by sublimation, not having been previously 

 treated with baryta:— 0-2225 grm. gave 0-5C9grm. carbonic 

 acid and 0'1190 water. 



II. Acid obtained as before from a new preparation: — 

 0*2105 grm. gave 0'540 grm. carbonic acid and O'll.SO water. 



III. Acid obtained from the lime salt: — 0"160grm. gave 

 0*4 15 grm. carbonic acid and 0-085 water. 



IV. Acid obtained from the baryta salt: — 0-3120 grm. 

 gave 0-803 grm. carbonic acid and 0-161 water. 



V. Acid obtained as before from a new preparation : — 

 0'320grm. gave 0-825 grm. carbonic acid and 0-1715 water. 



These numbers correspond to the following per-centages : — 

 I. II. III. IV. V. 



Carbon . G9-74 09-96 70-09 70-19 70-.31 



Hydrogen 5-91 5-96 5-98 5-98 5-95 



