

Action of Nitric Acid on Sebacic Acid. 421 



I may here mention an easy method of obtaining perfectly 

 snow-white sebacic acid, this material having generally a yellow- 

 ish tint. It is sufficient, just to boil one part of impure sebacic 

 acid with 5-6 parts of nitric acid, spec. gr. 1-35, and then mix the 

 solution with a great quantity of boiling water ; by cooling, the 

 sebacic acid crystallizes perfectly pure. 



The rest of the solution of sebacic acid in nitric acid, was kept 

 continually boiling, till the entire cessation of the formation of 

 nitric oxyd, constantly renewing the evaporating nitric acid. 

 The oxydation takes place very slowly ; it required eight days 

 for a quantity of about 200 grains of sebacic acid. After the 

 solution had changed its orange to a nearly white color, and the 

 development of nitric oxyd ceased, the contents of the matrass 

 were poured into a flat basin, diluted with an equal volume of 

 water, and on the waterbath the nitric acid slowly driven off, 

 using the precaution of adding from time to time a small quantity 

 of water. The white residue was then dissolved in water, filtered 

 and evaporated to a syrup, on the waterbath ; then allowed to 

 crystallize over sulphuric acid. Regular crystals could not be 

 obtained perhaps, because the quantity of the solution was not 

 sufficient ; but the whole solution solidified very soon and became 

 a white crystalline mass somewhat sticky, appearing like pure 

 grape sugar crystallized in a similar way. This substance, in a 

 perfectly pure state, is a strong acid, and the only product which 

 results from the action of nitric acid on sebacic acid. It is, as 

 will presently be proved, identical in composition and quality with 

 pyrotartaric acid, as far as a comparison was possible with the 

 fluctuating reports we possess about the latter. 



For analysis, the acid was dried over sulphuric acid, and after- 

 wards melted, but without sustaining any loss in its previous 

 weight ; it was burnt with chromate of lead and gave the follow- 

 ing results : 



(1*) 0*349 grm. substance gave 0-579 grm. carbonic acid, and 

 01915 grm. water. 



(2.) 0-3293 grm. substance gave 0*5485 grm. carbonic acid, 

 and 0-1805 grm. water. 



From this is derived the formula : 



C *H, 



°< 



=c, 



; H a 







3 HO=hydrc 



ite of pyrotan 



taric aci 











Ca) 



culated. 



Fou M 



j. 





I. 



ir. 



C, 







30 





45-45 



45-27 



45J2 



5 



H 4 







4 





6 06 



6 09 



6-09 



4 



o 4 







32 



7w 





48-49 



48-64 



48-49 



c 5 



H 4 



o 4 = 



100 00 



100 00 



100 00 



