CARBON IN ORGANIC SUBSTANCES BY THE KJELDAHL METHOD. 745 



the nitrogenous compound." Regarding the action of the permanganate of potassium, 

 he says (pp. 335 and 336) : " In the hot acid the added permanganate of potassium 

 decomposes the compounds of an organic nature still present in the fluid. The nitro- 

 genous part is chiefly so split up that a part or the whole of the nitrogen is converted 

 into ammonia. ... In the quantitative estimation of nitrogen, the oxidation with 

 permanganate can be very advantageously used. Care must, however, be taken that 

 the substance has been long enough heated previously (with the acid) and also that not 

 too much be added." 



Kjeldahl had previously pointed out that the sulphuric acid must first so far decom- 

 pose the substance to enable the permanganate to finish the reaction without loss of 

 nitrogen. 



Regarding the action of sulphate of copper and mercury, these undoubtedly hasten 

 the reaction. They act probably as oxygen carriers to the substance, being alternately 

 oxidised and reduced. They are not, however, generally applicable. He says (p. 347) : 

 " Bodies which have little resistance to the action of sulphuric acid can suffer a loss of 

 nitrogen by the presence of these metallic substances causing too active an oxidation 

 while the ammonia is being formed by the action of the sulphuric acid." He concludes, 

 from his research, that the Kjeldahl process is applicable to all amides and ammonium 

 bases, pyridin and quinoline bodies, the alkaloids, albuminoid substances, &c. 



Estimation of Carbon in Organic Substances by the Kjeldahl Method. 



In the Archiv fur Hygiene, Band xiv., 1892, p. 364, Dr Okada of Tokio described 

 an apparatus for this purpose, and gave a table showing his results. Fig. 1 is copied 

 from his paper. (A) is the flask in which the oxidation takes place, and is fitted with 

 a ground in glass tube which leads to an Erlenmyer's flask containing 100 c.c. distilled 

 water (B). This flask has two other tubes, one connecting it with the Wolffs bottle 

 (C) and another connecting it with a wash-bottle (G) containing baryta water. The 

 Wolffs bottle (C) is nearly one-half filled with a saturated solution of permanganate of 

 potassium and is connected with a Pettenkofer's carbonic absorption tube (D), and this in 

 turn with a water-pump. The capacity of (D) is over 300 c.c.'s. In conducting an experi- 

 ment, 20 c.c. of strong sulphuric acid and a small quantity of metallic mercury are put 

 into the flask (A), and then the amount of substance to be used, contained in a tinfoil boat, 

 is added. 300 c.c. of a strong baryta solution (37 grammes barium hydrate and 3*7 

 grammes barium chloride to 1 litre) is put into the absorption tube. A flame is applied 

 to the flask and the pump turned on to cause a slow current of air entering at the wash- 

 bottle (G) in the direction of the Pettenkofer absorption tube. When the reaction is 

 finished, i.e., when the sulphuric acid is colourless, air is allowed to pass through the 

 apparatus some time longer ; the apparatus is then opened, the flame put out, and the 

 contents of the absorption tube poured into a tightly stoppered bottle and set aside to 



