Vol. 19,No. 11
INDUSTRIAL AND ENGIYEERING CHEMISTRY
1296
hot alkali, and much of the steam produced in the boiling chamber condenses before it reaches the distillation flask. The apparatus illustrated was designed to prevent the condensation of steam and make it possible to attach it to a single ringstand. It is built entirely of Pyrex, eliminating all rubber connections. The steam generator, A , is made from a 500-cc. Kjeldahl flask sealed to the chamber E , with openings a t L and K to allow the steam t o pass through B , E , F , and M to the distilling flask, N . Ammonia-free water is added t o A through the funnel D and a blank run to make sure that the water or apparatus does not contain ammonia. The digested sample and an r
M
-
Pregl3 recommends distillation of the ammonia into N/70 hydrochloric acid and titration of the excess with N/70 sodium hydroxide, using methyl red as an indicator. In order to prevent solution of the alkali from the condenser tube by t h e distillate he substituted a silica tube, which is easily broken. With a Pyrex tube in the condenser no appreciable error due to the solution of the glass by the distillate has been detected. Results that equal those found by nesslerization were obtained by collecting the distillate in an excess of N/100 sulfuric acid and titrating back with N/100 sodium hydroxide using methyl red as indicator. Where the sample contains a large amount of nitrogen the titration is preferable t o nesslerization. Results
The results in Table I indicate the accuracy of the apparatus and method as used on samples of ammonium chloride. Table I1 shows typical results of over three hundred determinations carried out on lake-water residues, as obtained by Mr. Rex Robinson. Table I-Xitrogen i n Samples of Ammonium Chloride XITROGEN P~ITROGEN INTRODUCED OBTAINED ME. Mg. 0.067 0.070 0.070 0.070 0.070 0.070 0.070 0.071 0.068 0.070
3
Table 11-Nitrogen i n Lake Residues WEIGHT O F NITROGEN SAMPLE SAMPLE OBTAINED Mg. Mg.ber liter 1 10.24 0.301 9.79 0.303 2 10.04 0.309 10.69 0.305 3 10.48 0.734 9.68 0.733 4 10.66 0.533 9.7s 0.523
@ p . cit., p . 97
Color Standards for Bone-Black Revivification Tests’ By Rene Baus
excess of potassium hydroxide are added to N through the funnel P. A trace of copper sulfate in the digested sample indicates when an excess of alkali has been added, The distillation is carried out with the stopcocks on the apparatus in the position indicated in the drawing. The condenser, T , is supplied with running water and small burners are placed under A and N . The steam generated in A passes to N , helps to liberate and carry the ammonia and steam through the tube H , and on passing through T is condensed and collected in a 50-cc. graduated flask containing 25 cc. of ammonia-free water. The condenser tube is placed below the surface of the liquid and 25 cc. of distillate are collected. The apparatus is prepared for the next sample by removing the burners and allowing the solution in N to be drawn into chamber E by the vacuum caused by the condensation of the steam. A small depression a t the bottom of flask N facilitates complete removal of the distilled sample. The distillation flask is rinsed by placing a burner under A and turning the three-way stopcock to connect C with LM. When sufficient water has siphoned in N , the stopcock is turned as in the illustration, the flame removed, and the rinse water sucked back into E as before. The tube S,t o which is attached a rubber tube closed with a pinchcock, is now opened and the used sample flows out. The apparatus is now ready for a second determination. Five minutes are required for a complete distillation. Nitrogen Determination An aliquot of the distillate, usually one-half, is diluted to 50 cc. in a Nessler tube, nesslerized, and compared with standards treated similarly and a t the same temperature.
GRAMERCY, LA.
E caustic soda test for thoroughness of char reviviTHfication has been used in sugar-refining for many years and has proved of great value in the control of kiln work. Good practice in making this test is to boil 60 grams (measured) of char with 75 ml. of 9 ” Brix caustic soda solution for 2 minutes in a covered 250-ml. copper beaker and then filter through paper or cotton into a test tube. The quality of revivification is judged from the color imparted to the caustic solution by organic matter which has not been thoroughly carbonized in the kiln. Absence of color indicates over-burning, well-burnt char gives only a faint lemon yellow, and any tendency towards a brown color indicates poor burning. A set of color standards for reference has value where several persons in a plant-as the control chemist, shift superintendent, and the charhouse foreman-are each guided by the results of the tests. Standards closely matching the yellow to brown color tone of the test and which are easily duplicated can be prepared from acidified solutions of the bromthymol blue dye which is used for p H work. Four standards, graded “orerburnt,” “ i d 1 burnt,” “mediocre,” and “poor” are sufficient for kiln control. These can be made up in the order given by adding to 35-ml, portions of 0.5 per cent acetic acid 0.25, 0.50, 1.0, and 2.0 ml. of 0.04 per cent bromthymol blue. This gives enough solution to fill the 175 by 20-mm. test tube used for comparisons, The standards will not fade for several weeks if tightly corked and sealed with paraffin. 1 Received
September 12, 1927.
