372 /. K. P helps — Combustion of Organic 



Art. XL. — The Combustion of Organic Substances in the 

 Wet Way; by I. K. Phelps. 



[Contributions from the Kent Chemical Laboratory of Tale University — LXVL] 



In a former paper* I have shown that carbon dioxide may 

 be estimated iodometrically with a fair degree of accuracy. 

 Inasmuch as this method is not dependent upon the rate of 

 flow or rapidity of generation of the carbon dioxide, it seemed 

 possible that some advantage might follow its application to 

 the determination of organic carbon, oxidized by liquid 

 reagents. 



Method of oxidation by Potassium Permanganate. 



The first experimental test in this direction was made with 

 oxalic acid, which was oxidized according to the well-known 

 reaction of potassium permanganate in the presence of sul- 

 phuric acid. The apparatus used was the same as that previ- 

 ously described in the iodometric process, referred to above. 

 It consisted, in the main, of an evolution flask and an absorp- 

 tion flask, properly connected. As an evolution flask, a wide- 

 mouthed flask of about 75 cm3 capacity was used. This was 

 closed by a doubly perforated rubber stopper, carrying a sepa- 

 rating funnel for the introduction of liquid into the flask and' 

 a glass tube of *T cm internal diameter, which was expanded to 

 a small bulb just above the stopper, to carry off the gas. This 

 exit tube was joined by means of a rubber connector to a tube 

 which passed through the rubber stopper of the absorption flask, 

 which was an ordinary round-bottom flask of 250 cm3 capacity. 

 This tube ended in a valve of the Kreider pattern, f which was 

 enclosed in a larger tube, reaching nearly to the bottom of the 

 absorption flask. The second hole of the stopper of this 

 absorption flask, was filled by a glass tube closed by a rubber 

 connector and screw pinch cock. 



The barium hydroxide solution for use in the determination 

 of the carbon dioxide was prepared by filtering a cold satu- 

 rated solution of the commercial salt into a large bottle, which 

 was connected with a self-feeding burette. The solution was 

 standardized in the manner described in my former paper by 

 boiling with an excess of decinormal iodine solution in an 

 ether wash bottle. The short tube of the glass ground stopper 

 of the bottle was sealed to a Will and Varrentrapp absorption 

 apparatus, which was charged during the operation with a solu- 

 tion of potassium iodide to prevent the loss of elementary 



* This Journal, vol. ii, p. 70. 

 f This Journal, 1, p. 132. 



