BOILER AND MANAGEMENT 335 
this needs to be done is, of course, dependent upon the 
amount and character of the impurity in the water. Boilers 
are kept clean in three different ways, (1) by blowing 
off at low pressure, (2) by cleaning through manhole, 
and (3) by using boiler compounds. 
(1). By blowing the boiler off at low pressure most 
of the mud will be blown out. But care must be taken 
that the pressure is not above ten pounds and that there is 
no more fire in the fire box, otherwise the mud, instead 
of flowing out with the water, will bake on and form 
scale. 
(2). A good way of removing mud is to allow the 
boiler to cool off and then run a rubber hose through the 
manhole. By working the hose and forcing water 
through it the sediment can be removed. 
(3) Boiler compounds are used to keep boilers free 
from scale. The kind of compound to be used is deter- 
mined by the character of the impurities of the water. 
Most dairies use well water for the boiler and the chief 
impurity in this is lime. The best compound for water 
of this kind is soda. Well water contains the lime in 
widely different proportions. In order, therefore, to as- 
certain the proportion of soda to feed water the following 
method is recommended by Hawkins: 
“tT. Add one sixteenth part of an ounce of soda to a 
gallon of the feed water and boil it. 2. When the sedi- 
ment thrown down by the boiling has settled to the bottom 
of the kettle, pour the clear water off and add one-half 
drachm of soda to this. Now, if the water remains clear, 
the soda which was put in has removed the lime. But 
if it becomes muddy, the second addition of soda is neces- 
In this way the amount of soda to be added to 
the feed water can be calculated with sufficient accuracy. 
’ 
sary.’ 
