I N D U S T R I A L A N D ENGINEERING CHEMISTRY
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From this table it is evident that the application of the curves derived for mixtures of the Pure cornsounds to the interpretation of values obtained on dynamite extractives would give results indicating a proportion of nitroglycerin much higher than that actually present. It is also apparent that the oils, fats, and resins present in dynamite extractives cannot be removed entirely by freezing. Marqueyrol and Goute13 described a cryoscopic method of analysis for mixtures of nitroglycerin with ethyleneglycol dinitrate, but the writer has found that, while fairly accurate for mixtures of the pure substances, it yields very erroneous results when applied to mixtures extracted from commercial explosives. This was attributed to the impossibility of entirely removing oils, fats, and resins by freezing, as recommended by Marqueyrol and Goutel, and the data for refractive indices Bull. soc. chim., 2T, 443 (1920).
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of such mixtures given above prove this conclusion to hold. Application of Method
Inasmuch as the oils naturally present in dynamite “dopes” vary eonsiderably and the types of greases used for graining purposes also vary to some extent, it is improbable that a satisfactory correction for the error caused by the presence of these substances could be determined and applied to a dynamite extractive. Accordingly, the application of the method and data, given in the case of commercial dynamites, must be restricted to the qualitative detection of the nitrates of the glycols. To the analysis of mixtures that have not dissolved oils and fats from other dynamite constituents, the method can be applied quantitatively, and so is of value in factory-control work.
Apparatus for Fractional Distillation under Reduced Pressure’ By Jacque C. Morrell and Gustav Egloff UNIVBRSAL OIL PRODUCTS COMPANY,CHICAGO, ILL
EVERAL years ago the authors described a new form of apparatus for the fractional distillation of liquid mixtures under reduced pressure.2 The present contribution relates to a modification of this apparatus, which is more convenient in form for general laboratory use than the original apparatus. Figure 1 shows the front elevation of the modified apparatus. The receivers are mounted vertically a t the same elevation instead of being placed one directly above the other. The operation of the apparatus is similar to that of the original design. A three-way mercury-sealed stopcock (2) with large passageways controls the flow of the distillate to t h e r e c e i v e r s . When a fraction has collected in one of the receivers, stopcock (2) is turned so that the distillate flows to the other. Stopcock (4),also a threew a y s t o p c o c k , is then opened to the atmosphere and closed to the equalizing or stabilizing reservoir connected to the vacuum pump. This change permits the w i t h d r a w a l of the fraction from the receiver through the draw-off stopcock (3). The second fraction is collected and withdrawn similarly. After a fraction has been removed the receiver is g r a d u a l l y
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1 Received July 1, 1927. Presented before the Division of Petroleum Chemistry at the 74th Meetina of the American Chemical Society, Detroit, Mich., Septemter 5 to 10, 1927. 9 J . SOC. Chcm I n d . , 42, 188T
connected with the stabilizing reservoir by means of stopcock (4) to reduce the pressure to that of the system. Figure 2 is a side elevation of the same apparatus that shows more clearly the arrangement of the equalizing bottle (5) and the stopcocks (4) for connecting the receiver with the system or the atmosphere. Acknowledgment
The writers wish to acknowledge a suggestion of 13. M. McClure, formerly of this laboratory, in the conversion of the original apparatus t o the present form.
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