eatest importance, and
the conduit requires to be frequently washed out and the sulphate of lead
removed. This sulphate always contains nitro-glycerine, and should
therefore be burnt in some spot far removed from any danger building or
magazine, as it frequently explodes with considerable violence.

[Illustration: FIG. 6.--SMALL NITRATOR. _N_, Tap for Discharging; _P_,
Water Pipes; _T_, Thermometer; _W_, Windows; _P'_, Glycerine Pipe.]

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 ex