14 BULLETIN 3879, U. S. DEPARTMENT OF AGRICULTURE. 
CHEMICAL FIRE EXTINGUISHERS. 
The chemical extinguishers in use were arranged to be tripped by 
hand. They consisted of a tank containing water charged with 
bicarbonate of soda and a bottle containing sulphuric acid. The 
tripping device either upset the bottle or hberated a hammer that 
broke it. The extinguishers in use in the field worked with varying 
degrees of success. 
WATER UNDER PRESSURE. 
A number of separators were equipped with water tanks that could 
be pumped to 100 pounds pressure by a special air pump and were 
provided with a system of piping from the tank to the separator 
much the same as was the chemical extinguisher. The results ob- 
tained did not appear to be satisfactory, possibly due to the fact 
that as soon as some of the water had sprayed. out the pressure 
dropped so rapidly that there was not sufficient pressure remaining 
to be effective. However, a number of machines were saved from 
total destruction by using this type of extinguisher. 
One machine was equipped with a 40-gallon water tank on top of 
the separator connected to the engine pump which maintained a 
pressure of 70 pounds. In case of fire, by the pulling of a wire, the 
pipes from the tank were opened and the water carried to per- 
forated pipes in the separator. As no fires occurred in this machine 
the tank did not receive a thorough trial. 
STEAM LINE FROM BOILER TO SEPARATOR. 
Steam or water hose from the engine boiler to the separator was 
used in many cases with satisfactory results. Its popularity was due 
to the comparative cheapness of the system (about $50 to $75) and 
- also to the success attributed to it by the men who had used it. Best 
results were obtained when regular steam hose was connected to a 
point on the boiler below the water line. When a valve was opened 
at the boiler a pressure of steam and water was obtained which 
usually was successful in extinguishing the fire. | 
Where it was difficult to secure steam hose and it was not consid- 
ered safe to use ordinary rubber hose the line was composed of 
steam pipe. This made a much more clumsy installation, but it 
worked successfully when necessary swinging joints were properly 
installed. 
FURTHER EXPERIMENTAL WORK. 
In addition to the investigations made in the field based on actual 
explosions and fires an attempt was made to study in the field or in 
the laboratory the following: 
