46 OPERATIONS OF FUEL-TESTING PLANT IN 1905. 
It is proposed to continue these investigations of the lignites until results are obtained 
which will show how they can be briquetted economically in the manner indicated above 
and, in general, how they can be utilized most efficiently. 
Concerning the possibility of briquetting bituminous coals without binding materials, 
by raising the temperature, and also concerning the possibility of decreasing the per- 
centage of binding material by raising the temperature of the coals preliminary to bri- 
quetting, a number of tests were made by Doctor Mills in the laboratory of the fuel-testing 
plant at St. Louis, but the results in each case were unsatisfactory, as they failed to indi- 
cate the probability of economic success in that direction. 
SOME GENERAL CONCLUSIONS. 
The successful development of a coal-briquet ting industry in the United States will 
depend on a number of conditions, some of which are variable. 
The condition which more than any other has prevented the development of such an 
industry in this country is the low price of bituminous coal and especially the small difference 
between the price of the lump coal and that of the slack, or fine coal. Especially is this latter 
phase of the problem illustrated by the coking coals of Pennsylvania and West Virginia, 
where much of the slack coal commands a price equal to or approximating that of the 
lump coal. Much of the lump coal is finally crushed before being manufactured into coke, 
and the slack coal even has the advantage in not having to be crushed. Furthermore, 
even where these coals are not used for the manufacture of coke, but are sold for general 
power purposes, much of the fine coal can be shipped and burned with the lump coal, for 
the reason that it fuses as soon as it begins to burn, and therefore does not to any serious 
extent sift down through the grate bars and either clog the draft or escape with the ashes, 
as is the case with noncoking coals. 
In the territory of the noncoking coals the demand for the slack coal is not so great, and it 
can in some places be bought at less than 50 cents per ton; while at a number of mines 
large quantities are thrown on the dump as waste, frequently being burned in order to 
gee rid of it. 
Perhaps in no country has specialized equipment for burning fine coal been carried so far as 
it has in the United States, but the results of a number of tests by engineers seem to indi- 
cate that with the noncoking coals the use of the finely powdered coal, even in the modern 
furnace, is a disadvantage rather than a gain, for the reason that this fine material sifts 
through onto the grates, is ultimately lost with the ashes, and meanwhile prevents a full 
draft, which is essential to rapid and complete combustion. This is, therefore, one class of 
material which should be separated from the coarser coals and made into briquettes, 
provided the price at which these briquettes can be sold is sufficient to more than cover 
the cost of manufacture. 
With anthracite and semianthracite coals the difference between the price of the lump 
coal and that of the slack is often more than sufficient to cover the cost of manufacturing 
briquettes, and in such cases there can be no question as to the possibility of establishing 
a briquetting industry as soon as the proper binding material and briquetting equipment 
can be provided. 
There are still other cases in which it is claimed that the difference between the prices 
of the lump coal and of the slack are either just sufficient, or scarcely sufficient, to cover 
the cost of briquette manufacture, but the fact that the briquettes made from this material 
present certain advantages over the lump coal make them command a sufficiently higher 
price to provide a margin of profit. 
Unfortunately the high cost of the pitch which is generally used as a binding material 
is one of the barriers now existing in the way of the development of this industry. One 
of the purposes of the present investigation is to discover, if possible, some cheaper binding 
material, and the outlook in that direction is encouraging. The cost of manufacturing 
briquettes in France, Germany, Belgium, and England, including all necessary items 
