6 BULLETIN" 717, U. S. DEPARTMENT OF AGRICULTURE. 
three-quarters of an hour, with the result that the combustible gases 
in the coal were distilled and escaped unconsumed up the chimney. 
Finally, holes were burned in the fire bed so that too much air was 
allowed to pass through, which cooled the boiler and setting and also 
carried a large part of the heat up the stack. 
The average quantity of coal per 1,000 pounds of butter made of 
all creameries studied was 1,140 pounds, though many of them pro- 
duced 1,000 pounds of butter with a fuel consumption considerably 
less than 400 pounds. 
The total quantity of factory-made butter in the United States, as 
reported by the Thirteenth Census (1910), was 627,145,865 pounds. 
If the quantity of coal were reduced to, say, 400 pounds per 1,000 
pounds of butter, the saving would approximate 232,000 tons annually 
in the creameries throughout the country, which at $5 a ton would 
amount to $1,160,000. 
CONSTRUCTION OF BOILER SETTINGS. 
In comparing and studying the itemized expense reports of a large 
number of creameries it was noted that in most cases the fuel item 
was excessive. It was extremely variable even in creameries which 
made practically the same quantity of butter annually. Further in- 
vestigations showed that this wide 'variation in the fuel consumed 
was due largely to one or more of the following causes: (1) Poor 
installation and maintenance of boilers and settings; (2) careless 
firing; (3) bad condition of engine and other steam-driven machin- 
ery; (4) failure to utilize the heat in the exhaust steam; and (5) lack 
of system in operating the plant. 
A common cause of fuel loss in the average creamery is faulty 
boiler setting. Most creamery boilers in use at the present time are. 
of the horizontal return-tubular type and require an external setting 
which is generally constructed of brick. The settings are usually 
built by local workmen who have had little or no experience in boiler 
work ; hence the construction is nearly always too light and flimsy to 
withstand the heat and the weight of the boiler and contained water. 
As a result the settings crack from the heat and weight and thus 
allow too much air to enter the furnace. This reduces the draft 
and also causes a direct heat loss, due to the heating of excess air. 
Warped and cracked firing doors also contribute to the heat loss 
by admitting more air into the furnace than is required for complete 
combustion. The economical burning of fuel requires not only the 
proper arrangement and proportioning of the furnace, combustion 
chamber, uptakes, breeching, and chimney, but also that they be 
practically air-tight. To burn fuel completely a definite quantity 
of air is required, which must be admitted at the proper place and 
time and be mixed thoroughly with the combustible gases. 
