Fig. 1.--Trauzl Lead Blocks.

Fig. 2.--Powder Flames.]

The apparatus is assembled on scales and weighed before the water is
poured in and after the receiver is filled. From the weight of the water
thus obtained and the rise of temperature, the calorific value may be
computed. The charge is exploded by electricity, while the water is
being stirred. The rise in the temperature of the water is read by a
magnifying glass, from a thermometer which measures temperature
differences of 0.01 degree. From the readings obtained, the maximum
temperature of explosion may be determined, according to certain
formulas for calorimetric experiments. Proper corrections are made for
the effects, on the temperature readings, of the formation of the
products of combustion, and for the heat-absorbing power of the
apparatus.

_Impact Machine._--In Building No. 17, at the south side, is an impact
machine designed to gauge the sensitiveness of explosives to shock. For
this purpose, a drop-hammer, constructed to meet the following
requirements, is used: A substantial, unyielding foundation; minimum
friction in the guide-grooves; and no escape or scattering of the
explosive when struck by the falling weight. This machine is modeled
after one used in Germany, but is much improved in details of
construction.

The apparatus, Fig. 1, Plate XI, consists essentially of the following
parts: An endless chain working in a vertical path and provided with
lugs; a steel anvil on which the charge of explosive is held by a steel