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calculated t o the volume on which 50 cc. were taken for analysis, and t o which was added the amount due t o occlusion as determined in a n acid solution by t h e DeRoode method. All of the Lindo-Gladding results are below the DeRoode results, the average being 0.19 pet cent. On the other hand three DeRoode results are higher and two lower t h a n the recalculated Lindo-Gladding results t o which occluded potash was added, and all analyses check within t h e limits of good analytical work. The value of this procedure was then tested in t h e presence of large amounts of organic matter. I n this work we used a cottonseed meal and a cottonseed meal mixture, the last two samples of Table IV. Table VI1 shows the results obtained. I t is well t o mention in this connection t h a t the moist combustion as prescribed ifi the DeRoode method gave perfectly clear solutions both with cottonseed meal and with the cottonseed meal mixture. It is quite difficult t o burn off cottonseed meal t o a white residue as prescribed in the Lindo-Gladding method. TABLEVII-ACCURACYOF THE DEROODEMETHOD IN THE PRESENCE . LARGEAMOUNTSO F ORGANIC MATTER
CSM C$M. Mix.
1.78 4.70
1.70 4.69
1.78 4.70
-0.08 -0.01
0.00 0.00
OF
-0.08 -0.01
I n the foregoing table the results are well within the limits of experimental error, therefore we went through t h e work as already reported in Table VI t o ascertain if the close agreement is due t o the balancing of the two sources of error already shown for the LindoGladding method. Table VI11 summarizes the results so obtained. Table VI11 shows t h a t cottonseed meals and fertilizers containing a large proportion of cottonseed meal
Vol.
11,
NO.
TI
show practically no occlusion, beyond the potash cantent of the volume occupied by the precipitate. TABLE VI11
We have already shown t h a t precipitated phosphates, as well as the hydroxides of iron and aluminum, occupy large volumes in the flask when the LindoGladding method is used.' Each bf the mixtures used in these studies contained a large percentage of phosphatic material, a n d in no case is there a n y indication t h a t this affected the accuracy of the DeRoode method. SUMMARY
I n summarizing we claim t h a t the DeRoode method as herein outlined is accurate in the presence of a n y amount of ammonium salts, organic matter, nitrate of soda, or phosphatic matter t h a t will be used in a manipulated fertilizer, or t h a t may be present in natural fertilizing materials. The method is easy of manipulation and dispenses with platinum apparatus; but above all else, i t is more accurate than the LindoGladding method, the latter method varying in accuracy with the kind and amounts of impurities present in the material. ACKNOWLEDGMENT
T h e work herein reported was begun b y us a t t h e South Carolina Experiment Station, and b y agreement with the director of t h a t station was continued and completed here. LABORATORY OF THE GEORGIA EXPERIMENT STATION EXPERIMENT, GEORGIA 1
L O G Lit.
LABORATORY AND PLANT A NITROGEN GENERATOR FOR LABORATORY USE By W. I,. B A D G ~ R Received June 26, 1919
The usual process for obtaining nitrogen in the laboratory depends on a furnace containing copper, whether the copper is used as the means of fixing the oxygen, or whether i t is merely an indicator, as in Hulett's meth0d.l Both are inconvehient; the first where considerable quantities of nitrogen are required, the second where a steady stream is wanted over a long period of time. Van Brunt2 describes an apparatus for the preparation of nitrogen for laboratory purposes by the use of copper and ammoniacal solution of an ammonium salt. His apparatus works satisfactorily, but is more complicated than is necessary; and the glass blowing required is a little difficult for many laboratory workers. The apparatus here 1
J . A m . Chem. SOL.,37 (1905), 1415.
2
Zbid., 86 (1914), 1448.
described was suggested by a desire t o simplify the above apparatus. A wide-mouthed bottle, A, is filled with the reagent and with as much metallic copper as can be got into it-preferably in the form of straight wires standing vertically, as this gives more thorough contact with the gas. B is a Liebig condenser shell with the lower water connection sealed off. It is filled with copper turnings or punchings. A tube, D, is connected t o the upper water connection, and goes nearly t o the bottom of the bottle A. At the upper end of the condenser should be a bulb, C, though the trap as shown is not necessary. The gas inlet should also go nearly t o the bottom of the bottle. The lower end of t h e condenser may be cut off a t an angle or left square. A fourth tube may be added for blowing out spent reagent, if desired. On passing in air or commercial nitrogen by the tube E, most of the oxygen is removed by the copper in the bottle, and the tower is usually
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needed only t o remove the last traces. Unless very large volumes of air are t o be run through, a copper column 4 or 5 in. high (if punchings are used) is quite sufficient. Where turnings are used, a much higher column is necessary t o present the same surface. The bottle should hold a couple of liters t o make frequent filling unnecessary. The reagent recommended is made by diluting one part of commercial ammonia with one part of water and saturating the mixture with ammonium chloride. This mixture is a quantitative absorbent of so oxygen until heavy a precipitate forms t h a t the apparatus is clogged. If the tube D is not a part of t h e apparatus there is a stagnation of reagent in the tower and t h a t becomes clogged long before the apparatus is exhausted. The tube D furnishes a slow circulation which effectually prevents stag7 nation in the tower. The circulation so obtained is not nearly as rapid as in Van Brunt’s apparatus, but is amply sufficient t o keep the tower in operation. T h a t this reagent gives very pure nitrogen is shown by the fact t h a t Fergusonl used this apparatus in his electrotitrimetric determination of iron; and after reaching the end-point, if the nitrogen so prepared was allowed t o flow for some minutes, no change in t h e end-point could be detected. Mr. R. K. MacAlpine2 of the chemistry laboratory of the University of Michigan used this apparatus t o prepare nitrogen for use in atomic weight work. He found t h a t the nitrogen so prepared, very slowly reduced a dilute chromate solution. The action was exceedingly slow and took some time for reduction enough t o cause a visible color change in a .solution of chromate so dilute t h a t the yellow color was just apparent. 1 2
THIS JOURNAL, 9 (1917), 941. Personal communication.
1053
Using 8 mm. glass tubing for connections and a tower containing about j in. of copper punchings, the author has been able t o p u t a stream of 95 per cent commercial nitrogen through this apparatus faster than ordinary Drechsel gas wash bottles could remove the ammonia, and yet the resulting gas gave no test for oxygen with colorless cuprous chloride solution. The introduction, following the generator, of a wash bottle containing a little cuprous chloride solution with some metallic copper is very useful in indicating a leak or other failure of the apparatus. CHEMICAL ENGINEERING LABORATORY UNIVERSITY O F MICHIGAN ANN AREOR, MICHIGAN
FAT EXTRACTION APPARATUS B y J. M. PPICKEL Received May 12, 1919
The fat extractor pictured here (Figs. I and 2 ) was designed by the writer and has now entered on the third year of its use in his laboratory. I t is compact so t h a n any other t h a t has and economical-more come under his notice. Twenty fat extractions are made simultaneously on one electric heater 41/2 x 2 4 in., ten on each side of the heater, as against a total of seven by the leading extractor of this general style mow on the market. About 1 5 cc. of ether, one-third
FIG. 1
t o one-half of which is recovered for future use, are required for each extraction. The ether is distilled off from the extract (recovered) by merely giving the condenser a slight t u r n on its axis; there is no interruption of the distillation and no time or ether lost in taking t h e apparatus apart, removing the substance extracted, putting in its place a tube or receiver for the ether, putting the apparatus together again, and starting up the distillation again.
