1876.1 -^1^ [Wootten. 



ject it to a process that shall form it into masses of moderate dimensions, 

 so that when thrown into a furnace, interstices may be left to allow of 

 access of air to the surface of the lumps, in the same manner as is the case 

 with ordinary lump coal ; or else special means must be provided to retain 

 and consume it in the furnace ; and peculiar appliances be made use of to 

 insure the passage of air through the fire-bed and its proper contact with 

 the fuel. In either case provision must be made as far as possible for the 

 prevention of the formation of large masses of clinker and the disposal of 

 the ash. 



The first method referred to, that of forming the coal waste into lumps 

 of proper dimensions, by the admixture of clay or bituminous matter, or 

 other cohesive material, can only be profitably employed when the cost of 

 the operation is less than that of mining and preparing coal at the colliery. 



Heretofore the largest proportion of the coal mined was from above the 

 water level, and the comparatively low rate at which such coal was mined 

 prevented the successful application of any processes for agglomeration. 



As the coal above the water level is being exhausted and deep mining 

 has become necessary, the increased cost has directed attention to the utili- 

 zation of the waste coal under consideration. 



A large investment of capital in machinery may bring the cost of manipu- 

 lation below that of mining ; but it is not likely that the run of the waste 

 coal heap can be utilized by any such process, as it contains so large a pro- 

 portion of foreign and incombustible material. 



It is obvious that if the coal in its minutely sub-divided state can be ad- 

 vantageously consumed by means of any process or device which shall be 

 moderately simple in its construction and no more expensive of mainten- 

 ance, than an ordinary boiler furnace, the problem of utilization of coal 

 waste will have been solved, and a very considerable economy in cost of 

 fuel attained. 



"With this object in view, a method of consuming the material in ques 

 tion has been devised and may be described as follows : 



Air is injected into a closed ash-pan by means of a steam jet passing 

 through one or more tubes. These tubes should be cylindrical, when 

 volume of air without much intensity is sufficient ; but when greater in- 

 tensity is desired, as in the furnace of a locomotive, they should each be 

 formed of two frustrums of cones, united at their smaller diameters ; the 

 proportions of the larger and smaller diameters varying with the degree of 

 intensity of blast required. 



The mingled air and vapor pass through a perforated fire-bed into the 

 fuel in the furnace, and are thus evenly distributed through the fire, the 

 fuel being spread over the fire-bed to a depth of about three inches. 



The fuel upon the grate is gently lifted by the blast from over the per- 

 forations, the finer particles floating upon the current until the carbon is 

 consumed ; a large proportion of the ash passing otf in a finely divided 

 state, with the draft out of the stack. 



The decomposition of the vapor in passing through the fire, results in 



