water.  At the top of the vessel there is a glass cylinder i, having a lateral outlet j directed into the funnel mouth of a pipe k leading to the prewash tank.  Over the cylinder i is a glass globe l, into which opens a pipe m for leading off fumes which may be promoted by a compressed air jet from a pipe r operating as an injector.  Into an opening of the glass dome l is inserted a vessel n, which is connected by a flexible pipe p to the glycerine tank, and from the bottom of n, which is perforated and covered with a disc perforated with holes registering with those through the bottom, this disc being connected by a stem with a knob q by which it can be turned so as to throttle or cut off passage of glycerine through the bottom. s is a thermometer for indicating the temperature of the contents of the vessel.

[Footnote A:  Eng.  Pat. 15,983, August 1901.]

[Illustration:  FIG. 7.—­NATHAN’S NITRATOR FOR NITRO-GLYCERINE. (a) Nitrating Vessel; (b) to Separating Vessel; (c) to Drowning Tank; (e) Nitrating Acids enter (f) to the Waste Acids; (g) Coils for Compressed Air; (h) Pipes for Cooling Water; (i) Glass Cylinder; (j) Outlet to k; (k) leading to Prewash Tank; (l) Glass Dome; (m) Pipe to lead off for Escape of Fumes; (n) Vessel; (p) Pipe conveying Glycerine; (q) Knob to turn off Glycerine; (r) Compressed Air Jet; (s) Thermometer.]

In operating with this apparatus the nitrating acid is introduced into the nitrating vessel by opening the cock of the pipe e.  The glycerine is then run in by introducing n and opening the valve at its bottom, the contents of the vessel being agitated by air blown through the perforations of the pipe g.  When the glycerine is all nitrated and the temperature has slightly fallen, the circulation of the water through the coils h and the air-stirring are stopped, and the glycerine supply vessel n is removed.  The nitro-glycerine as it separates from the acids is raised by introducing by the pipe f waste acid from a previous charge, this displacing the nitro-glycerine upwards and causing it to flow by the outlet, j and pipe k to the prewash tank.  When nearly all the nitro-glycerine has been separated in this manner the acids in the apparatus may be run off by the pipe b to an after separating vessel for further settling, thus leaving the apparatus free for another nitration, or the nitrating vessel itself may be used as an after separating bottle displacing the nitro-glycerine with waste acid as it rises to the top, or skimming off in the usual manner.  When the separation of the nitro-glycerine is complete the waste acid is run off and denitrated as usual, a portion of it being reserved for the displacement of the nitro-glycerine in a subsequent operation.