„ „,„,.,, GEOLOGY ROCKS EAST OF FRONT RANGE LIGNITIC. 117 



M-ARvTNE. j 



APPLIOATIONS. 



These coals have been fouud to serve well for all clomeistic purposes, 

 either for cooking or warming-, and are now largely nsed both for sta- 

 tionary boilers afld locomotives. Their freedom from sulphur, in ren- 

 dering them less injurious in burning out grate-bars, &c., would recom- 

 mend them for these purposes; though with some of these coals a 

 frequent use of the exhaust in increasing the draught is necessary to 

 insure a sufficiently rapid combustion. According to Hodge, the engi- 

 neers find that the more crumbling varieties sift through the grate-bars, 

 requiring closer screens at the top of the smoke-stacks. " They endeavor 

 to obtain the coal as freshly mined as possible, on account of its sounder 

 condition. Clinkers sometimes form sufficiently to be troublesome when 

 the coals are obtained from those mines that contain seams of slate." 



These coals are at present also used for the following purposes, for 

 information about which I am indebted to Mr. Berthoud : At the two 

 smelting works at Golden City the best lignitic coal is used in roasting 

 ores, either inclose furnaces, or in step-furnaces used in desulphurizing 

 pyritous ores. It is also used at Golden for baking the bricks, &c., 

 there made from the clays of the lignitic series. For gas-making in 

 Colorado the lignitic coals are alone used, while a five-feet bed at Golden 

 City, Canon City coal, and 'Trinidad coal are all used in blacksmith- 

 work. 



And here we seem to stand on the limits of the usefulness of these 

 coals. Notwithstanding the high potential calorific power which we 

 have seen that they possess, it remains for some reason unavailable. 

 For all those processes in the arts in which high temperatures are 

 required, the lignitic coals — as compared with anthracite and bitumin- 

 ous coals — have so far i)roved seriously defective. Indeed, they hardly 

 compare with some of the coals with which they are allied in both 

 physical and chemical features, as, for instance, the "block-coal" of 

 Indiana, which, though not equaling in calorific power some of these 

 western Goals, as Eaymond has shown, yet is successfully used in 

 smelting iron. With these coals, however, even for common black- 

 smithing purposes, it has required much experience before they have 

 become to be permanently used for welding, and, while they are used at 

 Golden City for roasting the ores, for smelting them (mostly galena, and 

 siliceous ores of gold, silver, copper, lead, and zinc) a large proportion 

 of Pittsburgh coke is used. One or two experiments in reverberatory 

 furnaces and several trials in blast furnaces have all proved unsuc- 

 cessful. In the former the common fire-box and horizontal grate was 

 used, and in no case was strong artificial draught or pressure employed. 

 What might be accomplished with the many recent appliances in the 

 way of improved grates, fire-boxes, and high pressures remains yet to 

 be seen, but, so far as tried, they have failed as producers of high 

 temperatures. 



The cause of all these failures appears to be due simply to the physical 

 behavior of the coal when heated — in giving ofi their large percentage 

 of moisture they crumble into small pieces. On the furnace-grate this 

 produces a layer not readily penetrated by sufficient air to support a 

 rapid combustion and consequent high temperature, and the frequent 

 stirrings necessary to avoid this difficulty introduces another in the loss 

 of heat incident upon the constant opening of the furnance-doors. In 

 the blast furnace the tendency to crumble is augmented by the super- 

 incumbent weight, so preventing the access of air that the furnace 

 nearly chills without reaching a smelting temperature. They might 



