146 PRELIMINARY REPORT ON COAL-TESTING PLANT, [bull. 261. 
of pitch the resultant briquette had no coherence, regardless of what 
pressure was used. With 2 per cent of wax and 4 per cent of pitch X 
a briquette was obtained which was similar to the one in which 13 pei 
cent of pitch X alone was used. It was, however, not a satisfactory 
product. 
ACID SLUDGE. 
Some acid sludge was received from the Gulf Refining Company, ol 
Port Arthur, Tex. It was mixed with water, and the resultant solu- 
tion was a weak acid which did not seriously attack iron. Part of this 
sludge was a thin, greasy mass and the remainder was of a rubbery, 
granular consistency. When these were heated together to the melt- 
ing point they did not mix, and on cooling they separated into the 
same two parts. The stiffer portion of the mixture will mix with 
melted rosin, and the resultant mass resembles the rubbery petroleum, 
B2. On account of lack of time no further work was attempted witli 
this acid sludge. 
LIME. 
No experiments were made with lime alone, as the percentage 
required for making a briquette that would hold together was so higl 
that it precluded entirely its use as a binder. The principal use I 
the lime was with rosin and molasses, and these experiments hav, 
been described under those heads. 
CLAY. 
Clay alone was tried up to 8 per cent, but in no case was a briquett 
obtained that would hold together on drying, although the clay use 
was a superier potter's clay. In making the laboratory briquettes tb:j 
clay was used only in connection with lignite, in order to determin 
its effect on the strengthening of the briquettes so that they woul 
hold together in burning. With 2 per cent of clay there was little o 
no effect noticed in the resultant briquette when rosin and the petr< 
leum, P2, were used. With 4 per cent of clay the quantity of til 
other two required was reduced from 6 per cent each to 5-J- per cei 
each, and the briquettes that were made from this mixture he 
together somewhat better in the fire. On account, however, of tl 
large increase in the percentage of ash caused by the clay no furth 
tests were made with a higher percentage of clay. 
BRIQUETTES MANUFACTURED. 
According to the results obtained in the laboratory, briquettes 
quantity were made on either the English or the American machi 
from the following coals: 
i 
