CONSTRUCTION AND FIRE PROTECTION OF COTTON WAREHOUSES. 21 
storage compartment, though openings frequently are necessary in 
compress compartments to connect them, or to connect the compress 
with the adjacent storage compartment. In any easel the opening 
should be as small as is practicable and should conform to the limi- 
tations stated later in the discussion of the doors themselves. Con- 
struction and design of fire doors is discussed in detail later. 1 
1 If brick is used they should be well burned and at least two-thirds of them 
hard (or fully burned), the " run-of-kiln guaranteed two-thirds hard" being 
satisfactory. Care should be taken to see that extremely soft brick from the 
outside of the kiln are thrown out. The harder^ brick of the lot should be 
used for the exposed surfaces of the wall, and the softer brick used for filling 
in between. 
The brick should be laid fairly close together with joints well filled with 
mortar. Ample " bond" or " header " courses should be used to tie the parts 
of the wall firmly together, this tie being used for every sixth course. The 
work should not be carried on in freezing weather, while if the weather is 
warm and dry the brick should be wet before they are laid, as this prevents 
too rapid drying of the mortar. The mortar used for the fire wall preferably 
should contain a mixture of one part Portland cemeut, one-seventh part lime 
(either putty or hydrated), and sand not exceeding three parts, and should 
be mixed only as required for use. A fairly satisfactory mortar for use above 
the ground, however, may contain one part Portland cement, one part lime 
(either putty or hydrated) and six parts sand. Cement should not be added 
more than one-half hour in advance of use of the mortar. 
When concrete is used, it should be prepared under competent supervision, 
while the actual work can be done largely by unskilled labor. Mixing and 
casting should not be done in freezing weather. Concrete not reinforced with 
steel should contain one part of Portland cement, two and a half or 3 parts 
sand, and five parts of suitable gravel or crushed stone. The chief dangers 
to be guarded against are leakage of the form in which casting is done, 
insufficient mixing, and careless packing or tamping. Concrete reinforced with 
steel, as used for walls, should conform to the requirements later stated in 
reference to " Reinforced concrete." The top of the opening should be formed 
by a substantial brick arch or a concrete lintel. Steel cr iron lintels may be 
used provided they are protected by either 4 inches of brickwork or a com- 
plete overlapping of the door. The threshold should be of iron or steel, se- 
curely anchored, or the sill (including the part against which the door closes) 
may be of concrete 6 inches or 9 inches thick and fully supported by the wall. 
An example of 4 by 4 inch steel angles used with concrete is shown by Plate 
XIV, figure 5. A solid cast-iron threshold with the surface roughened is to be 
preferred. The threshold should be raised 1% inches or 2 inches, with the floor 
sloped up to this level, so that water used to extinguish fire in one compart- 
ment will not flow into the one adjoining. 
Vestibule doorways afford excelleut protection of the opening. An example 
of such an arrangement is shown by Plate XIV, figure 6, where the low story 
makes the arrangement shown fairly economical. Where the story is very high 
the vestibule may be constructed with a low ceiling covering slab. The width 
of the vestibule corresponds to the width of doors, while for the depth, or dis- 
tance provided between the doors, 6 feet is sufficient unless it is desired to use 
one swining door opening into the vestibule, as is shown by the drawing. In 
such sase the minimum distance of 6 feet would be increased to suit the width 
of door used. 
