BRIQUETTING TESTS. 
By J. A. Holmes. 
CHANGES IX EQUIPMENT. 
The briquette machine used in the larger part of the testing work during 1905 was the 
one built by Wm. Johnson & Sons, of Leeds, England, referred to in the reports of this 
work for 1904. « The American machine referred to in the same report was returned to the 
owners at the end of 1904. Briquettes made on the English machine during 1904 meas- 
ured 4| by 6} by 5^ inches and averaged in weight 6.8 pounds. To obtain a briquette 
that would more nearly fulfill the requirements of domestic use and of stationary and loco- 
motive boiler practice, it was thought advisable to reduce the size. To this end the mold 
wheel on the machine was planed down so as to make a briquette 1\ inches (instead of b\ 
inches) in thickness, the other dimensions remaining the same. By adjusting the machine 
to meet this change it was possible to make satisfactory briquettes weighing about Z\ 
pounds, and these were used in the tests mentioned below. 
With a view to obtaining a greater range in the size of the crushed fuel for the briquettes, 
a series of pulleys was installed on the driving and driven shafts operating the disintegrator, 
giving approximately 80, 65, and 50 per cent of its original speed. The necessary improve- 
ments were also made in the construction of this machine, such as a wider driving belt, 
extension of the elevator feeding the pug mill, proper drainage for the exhaust pipe, jack- 
eting steam pipes, etc. By these improvements easier and more continuous operation 
was secured. 
To determine with a fair degree of accuracy the percentage of binder being used with each 
fuel in the English briquetting machine, a gate was placed at the point where the small 
screw conveyor discharges the pitch into the mixing screw conveyor containing the coal. 
The percentage of binder was determined by weighing coal and binder, and, by experiment, 
the proper opening of the gate for each percentage of binder was determined. 
PERSONNEL,. 
Mr. C. T. Malcolmson, the mechanical engineer in charge of the general work about the 
fuel-testing plant, has made the alterations in the briquetting equipment mentioned above 
and has also conducted the tests made on the English briquette machine. Prof. A. A. 
Steel, of the University of Arkansas, who superintended this work during 1904, has aided 
in the tests of 1905 in an advisory capacity. Dr. J. E. Mills, of the University of North 
Carolina, who served as chemist of this division from May 1 to October 6, 1905, conducted 
a series of laboratory experiments on the relative merits of different binding materials 
referred to in the following section. 
aBull. U. S. Geol. Survey No. 261, 1905, p. 13; Prof. Paper U. S. Geol. Survey No. 48, 1906, p. 25. 
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