krnald.] PRODUCER-GAS TESTS. 87 
wo tests per week, each of thirty consecutive hours, allowing suffi- 
ient time between tests to make the necessaiw change of fuel and to 
nahle the fuel bed in the producer to be brought to a proper 
vorking condition. 
As it was desired to test as many coals as possible in the few weeks 
emaining before the close of the Exposition, the highest possible 
economy was made a secondary consideration, and for a part of the 
ime the plant was run with a leaky hopper and other unfortunate 
Conditions, which naturally impaired its efficiency. 
In comparing the results it should be borne in mind that in these 
)reliminary tests the object has been to demonstrate the possibility of 
ising these coals in a producer, and not to show how efficiently they 
ould be burned. Although the results in many cases have been highly 
atisfactory, there is no question that in a second series of tests upon 
he same coals, made with the idea of showing the greatest economy, 
le amount of coal per horsepower per hour will, in the majority of 
ases, be much less. 
During tests Nos. 5 to 1-t inclusive the hopper of the gas producer 
?aked, and considerable gas was wasted, thus vitiating to a small but 
redetermined extent the efficiency results that might otherwise be 
aown for the coals tested during that period. But at the time of 
laking these tests it was not practicable to stop the operations of the 
lant for repairs; and the main purpose of the preliminary tests being 
3 determine whether the coals were suitable for producer-gas purposes, 
; was decided to proceed, in spite of the leak in the hopper, and to 
Bpeat later, under more favorable conditions, the tests for relative 
fficiency. 
These points should be kept carefully in mind in examining the 
ppended report, and criticism of the relatively poor showing of one 
pal as compared with another should be reserved until after the pub- 
cation of the detailed report, which will give a full statement of the 
pnditions under which each coal was tested and the influences that 
mded to make that particular test more or less favorable when com- 
ared with others. 
The results show with what ease gas may be produced from bitumi- 
pus coal and lignites, and, taken as a whole, indicate the satisfactory 
xmomic results that may be expected under ordinary working 
pnditions. 
I Immediately after the close of the Exposition, it having been decided 
> continue the tests for some weeks longer, the plant was shut down 
i order to repair the leaking hopper and to prepare for cold weather. 
Iperations were resumed on December 12 and continued until Decem- 
&r 22, which is the close of the period covered by this report. 
j A glance at the logs of the tests shows very clearly the advisability 
: allowing a few hours for the manipulation of the plant after start- 
