everything possible should be done to keep them as cool as possible in the
summer. With this object they should be made double, and the intervening
space filled with cinders. The roof also should be kept whitewashed, and
the windows painted over thinly with white paint. A thermometer should be
suspended in every house. It is very essential that the floors of all
these buildings should be washed every day before the work-people leave.
In case any nitro-glycerine is spilt upon the floors, after sponging it up
as far as possible, the floor should be washed with an alcoholic solution
of soda or potash to decompose the nitro-glycerine, which it does
according to the equation[A]--

C_{3}H_{5}(NO_{3})_{3} + 3KOH = C_{3}H_{8}O_{3} + 3KNO_{3}.

[Footnote A: See also Berthelot, _Comptes Rendus_, 1900, 131[12], 519-
521.]

Every one employed in the buildings should wear list or sewn leather
shoes, which of course must be worn in the buildings only. The various
houses should be connected by paths laid with cinders, or boarded with
planks, and any loose sand about the site of the works should be covered
over with turf or cinders, to prevent its blowing about and getting into
the buildings. It is also of importance that stand pipes should be placed
about the works with a good pressure of water, the necessary hose being
kept in certain known places where they can be at once got at in the case
of fire, such as the danger area laboratory, the foreman's office, &c. It
is also desirable that the above precautions against fire should be tested
once a week. With regard to the heating of the various buildings in the
winter, steam pipes only should be used, and should be brought from a
boiler-house outside the danger area, and should be covered with
kieselguhr or fossil meal and tarred canvas. These pipes may be supported