374 



1. K. Phelps— Combustion of Organic 



boiling point again, after which iodine was again run in but 

 this time to the permanent red color of the excess of free 

 iodine. After cooling, this excess of iodine was determined 

 by titration with decinormal arsenious acid solution. Thus, 

 the excess of barium hydroxide used being determined by the 

 iodine lost, the barium hydroxide used, now in the form of 

 carbonate, was known, from which the carbon dioxide which 

 precipitated this carbonate, may be calculated. 



The following results were obtained by this procedure. 









Table 



I. 









Ammonium 











Error 





oxalate 



Ba0 2 H 2 



Ba0 2 H 2 



co 2 



C0 2 



on 





taken. 



taken. 



found. 



fouud. 



calculated. 



C0 2 . 





grm. 



grm. 



grm. 



grm. 



grm. 



grm. 



1. 



0*2522 



0-7267 



01170 



0-1565 



0-1561 



0-0004 + 



2. 



0*2542 



0-7267 



0-1113 



0-1579 



0-1574 



0-0005 + 



3. 



0-5020 



1-4535 



6-2417 



0-3110 



0-3108 



0-0002 + 



4. 



0-5058 



1-3954 



0-1753 



0*3131 



0-3131 



o-oooo± 



5. 



1-0033 



2-6163 



0-1955 



0-6213 



06211 



0-0002 + 



6. 



1-0003 



2-5951 



0-1836 



06189 



0-6192 



0-0003 — 



7. 



1-0010 



2-6163 



0-2037 



0-6192 



0-6197 



0-0005 — 



In. experiments (5) and (6), a few drops of ammonia were 

 added to the oxalate solution before running in the perman- 

 ganate ; in (3) and (7), the permanganate was treated to alka- 

 linity with barium hydroxide ; in the remaining experiments, 

 (1), (2) and (4), the permanganate was slightly acid with the 

 sulphuric acid used in its purification from carbon dioxide, as 

 already described. The results obtained are good and it is 

 plain that the oxidation proceeded regularly, whether the first 

 action of the permanganate was in the alkaline or slightly acid 

 solution. 



Jones'* has shown that formates may be determined volu- 

 metrically by titration with potassium permanganate in alkaline 

 solution. In an attempt to determine formates by the process 

 outlined above, the pure barium salt was used. This was pre- 

 pared by treating the aqueous solution of formic acid with 

 pure barium carbonate to neutrality and crystallizing the 

 product. It was proven pure by ignition and weighing in the 

 form of carbonate. 



In making determinations of carbon in this formate, weighed 

 portions were introduced into the boiling flask, together with 

 sodium hydroxide solution, which was taken in such quantity 

 as to more than neutralize the acid in the potassium perman- 

 ganate. Naturally, the sodium hydroxide must be free from 

 * Amer. Chem. Jour., xvii, 539. 



