298 ANNUAL REPORT 
efficiency of a producer the amount of steam in the gas should be fre- 
quently determined by absorption and weighing the condensed steam. 
' By keeping the generator as cool and the amount of steam as small as 
possible, it will give no trouble as a rule. It is also of importance to 
have the generator sufficiently large so as to supply all of the gas needed 
with ease, without forcing the combustion too rapidly. It is much better 
to have two larger generators in place of four smaller ones. The gas should 
be conducted into the kilns through as short a flue as possible, so as 
to avoid the loss of the tarry matter which otherwise deposits. Gas 
firing should invariably be connected with regeneration, that is, using the 
waste heat of the kiln for pre-heating the air to be mixed with the 
producer gas. Without regeneration the system of gas firing loses much 
of its value. 
No one should employ producer gas if it is at all possible to use 
suitable coal for direct firing. Gas firing can never become fully as ef- 
ficient as dust coal firing, as certain losses, both chemical and mechanical 
are bound to occur. Some of these heat losses of a gas generator are 
shown in the following tabulation: 
Assumed total calorific power of coal, 8,198 calories per kilogram. 
Per cent of 
total heat 
Calories. generated. 
Rotentialeheat lostpnvashvorsca; Ooh ennai 483 5.9 
Latent heat of volatilization.............. East enn oo 600 so 
Decomposition and) heatine ofsteamenn se. ae eee ee 356 4.3 
Raciatronsandeconduchone erie a aan nn: iene er 355 4.3 
Sensible sheatok Cas iacnt wiry Oe eer ee ness tee eee 1,085 13}. 
Total losstofheats <ecseeo eae e  ee e 2,879 35.0 
Some loss would occur under these same heads in direct firing, but 
not in as great degree, the difference being about 15 per cent. in favor of 
direct firing. 
Ohio Coals. —It is impossible to give a discussion of the available Ohio 
coals in this report, a subject so admirably treated by the late Dr. Edward 
Orton, Sr., in his various reports of the Ohio Geological Survey. The 
writer will restrict himself to giving the analyses of a number of coals 
more especially available for cement burning. 
The analyses on the following table showing the calorific powers have 
been obtained through the kindness of Prof. N. W. Lord in advance of 
his report on the constitution and chemical properties of the Ohio coals to 
be published by this Survey. Though some of its best coal fields have 
been largely exploited, Ohio still has large quantities of coal suitable for 
cement purposes. 
