The fluctuation of the time required to extinguish a flame by means of sprays of several salt solutions was investigated.
The spray was projected vertically downwards to the fires of hexane burning in a cup 8cm in diameter.
The spray nozzle was mounted 70cm above the cup and when the discharge pressure was 3.5kg/cm², the amount of water reached the cup was 0.027ml/sec cm².
The measured extinction times showed relatively wide range of scattering and when many measurements were repeated under the nominally identical conditions, it was found that the frequency distribution had positively skewed shape. Considering the experimental results it was concluded that average value of several measurements of extinction times was not sufficient to express the extinguishing effectiveness of salt solutions.
The consideration of the statistical feature of the frequency distribution was necessary to understand the effect of addition of salt.

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Synopsis
For the smoke prevention design of the building, it is necessary to know what amount of smoke flow out to the corridor from the room.
In this purpose series of experiments have been made.
One is the material test using an electric furnace and another is the model box test.
1) Electric furnace test
The amount of smoke generation C is given as follows
C=C_s × V
Where V is volume (m³) in which the smoke is dispersed and C_s is the attenuation coefficient (1/m).
Smoke generation is assumed to be proportional to the disintegration of material and the ratio between smoke density and weight loss depends remarkably on the ambient temperature of specimen.
That is
C=C_s· V=K(_T)W
Where K(_T) is the smoke generation coefficient, W is the weight loss.
In the relation between the smoke generating coefficient and ambient temperature clearly two different portion can be seen one, is the portion of the smoldering burn and another the flaming burn.
Both relation under smoldering burn and flaming one can be derived as follows,
K(_T) = (A-BTⁿ)
Where T is ambient temperature. The rate of burning of specimen depends on the temperature and is expected of the following relation.
r=dw/dt=K₀W₀exp(-E/RT)
where w₀ is weight of specimen, R the gas constant, E the activation energy, T the absolute temperature and K₀ constant value.
Then the rate of smoke generation dc/dt in case of these specimen is
dc/dt=K · dw/dt
=(A-BTⁿ) · (K₀W₀exp(-E/RT))
2) Model Box Test
In the model box burning rate and smoke generating coefficient depends on rate of A √H and combustible internal lining area (As).
Where A is opening area (m²) and H is height of opening.
Approximately the model box fire is assumed to be depend on opening factor (A √H/As).
In the case of A√H/As is larger than 0.5 value of burning rate and smoke generating coefficient shows constant, A√H/As is smaller than 0.5 value of burning rate is proportional to A√H/As, but smoke generating coefficient to be increase by insufficient of air.

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An investigation of thermal decomposition of wood and its component cellulose and lignin is described, in which the action of some chemicals on decomposition was investigated by means of gaschromatographic analysis and elementary analysis. A remarkable point of this work is whether there is a difference or not when the chemicals was used as a fire-retardant or as a fire-extinguishing agent of wood fires: in which the former had penetrated into materials before decomposition, whereas the later had done after or then at least. And another point is consideration of chemical action on gasgenerating, which is very important for flaming wood.
The result showed the larger effect in such a case that the materials penetrated into as a fluid, which was a fused chemicals or a generated one by thermal decomposition at the adequate temperature. In the point that the chemicals used for fire-extinguishing agent of wood fire is necessary to penetrate into, it is different from one used for fire-retardant.
The author express his approval to the opinion that the action of penetrated chemicals into wood is a action of hydrogen ion or the like having in them, for example, hydrogen chloride from ammonium chloride, ammonium bisulfate from ammonium sulfate, metaphosphoric acid from ammonium biphosphate, and cyanuric acid from urea.

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