Theoretical organic chemistry / by Julius B. Cohen.

  • Julius B. Cohen
Date:
1902
Catalogue details

Licence: Public Domain Mark

Credit: Theoretical organic chemistry / by Julius B. Cohen. Source: Wellcome Collection.

    42/604 (page 22)
    i o-5 6 per cent, of N. f is the vapour tension of the potash solution, which may be taken without serious error to be equal to that of water. The volume, corrected to o and 760 mms., will be given by the following expression :— v x 273 x (B -/). (273 + t) 760 As the weight of 1 c.c. of nitrogen at o and 760 mms. is o‘ooi26gram, the percentage weight of nitrogen in the substance w will be given by the expression— v x 273 x (B-/) '00126 x 100. (273 + /) 760 zu Exampic.—o'2o6 gram of substance gave 188 c.c. of moist N at 170 and 756 mms. (f at 170 = 14*5 nuns.). 18*8 x 273 x (756 - 14'5) x *126 (273 + 17) x 760 x -206 Kjeldahl’s Method.—The substance is boiled for a time with concentrated sulphuric acid and potassium sulphate, a little potassium per¬ manganate or persul¬ phate being subse¬ quently added. The acid, which at first darkens in colour, then becomes colourless. The nitrogen is now present as ammonium sulphate. The liquid is then made alkaline with caustic soda and boiled, or steam is passed through to drive off the ammonia, the ammonia being ab¬ sorbed in a receiver containing a known volume of standard hydrochloric or sul¬ phuric acid. The apparatus is shown in Fig. 18. The flask a contains the ammonium sulphate, caustic soda is introduced