In works where the manufacture of nitro-glycerine is of secondary importance, and some explosive containing only perhaps 10 per cent. of nitroglycerine is manufactured, and where 50 or 100 lbs. of glycerine are nitrated at one time, a very much smaller nitrating apparatus than the one that has been already described will be probably all that is required.  In this case the form of apparatus shown in Fig. 6 will be found very satisfactory.  It should be made of stout lead (all lead used for tanks, &c., must be “chemical lead"), and may be made to hold 50 or 100 lbs. as found most convenient.  This nitrator can very well be placed in the same house as the separator; in fact, where such a small quantity of nitro-glycerine is required, the whole series of operations, nitrating, separation, and washing, &c., may very well be performed in the same building.  It will of course be necessary to place the nitrator on a higher level than the separator, but this can easily be done by having platforms of different heights, the nitration being performed upon the highest.  The construction of this nitrator is essentially the same as in the larger one, the shape only being somewhat different.  Two water coils will probably be enough, and one thermometer.  It will not be necessary to cover this form in with woodwork.

The Nathan Nitrator.[A]—­This nitrator is the patent of Lt.  Col.  F.L.  Nathan and Messrs J.M.  Thomson and W. Rintoul of Waltham Abbey, and will probably before long entirely supersede all the other forms of nitrator on account of its efficiency and economy of working.  With this nitrator it is possible to obtain from 2.21 to 2.22 parts of nitro-glycerine from every 1 part of glycerine.  The apparatus is so arranged that the nitration of the glycerine, the separation of nitro-glycerine produced, as well as the operation of “after-separation,” are carried out in one vessel.  The usual nitrating vessel is provided with an acid inlet pipe at the bottom, and a glass separation cylinder with a lateral exit or overflow pipe at the top.  This cylinder is covered by a glass hood or bell jar during nitration to direct the escaping air and fumes into a fume pipe where the flow of the latter may be assisted by an air injector.  The lateral pipe in the separation cylinder is in connection with a funnel leading to the prewash tank.  The drawing (Fig. 7) shows a vertical section of the apparatus; a is the nitrating vessel of usual construction, having at the bottom an acid inlet pipe with three branches, one leading to the de-nitrating plant, c leading to the drowning tank, and d, which extends upwards and has two branches, e leading to the nitrating acids tank, and f to the waste acid tank.  On the sloped bottom of the nitrating vessel a lies a coil g of perforated pipe for blowing air, and there are in the vessel several coils h, three shown in the drawing, for circulation of cooling