47'2 ANNUAL REPORT OF THE Off. Doc. 



Coal for Domestic Use 



For domestic purposes, a coal is desired that burns steadily and 

 will remain ignited at a low temperature until consumed. Such con- 

 ditions can not be obtained from a true bituminous coal, because it 

 burns too freely and is difficult to control. Again, the high volatile 

 coals, if burned in open grates or stoves, not only throws out soot 

 and dirt but clog the chimneys. Such coals, if high in sulphur, are 

 extremeh^ objectionable, not only on account of the odor thrown off, 

 but because of their tendency to corrode grates and pipes. A coal 

 forming clinkers at a low temperature is undesirable, since such will 

 check the draft by clinging to the grate bars. A coking coal is also 

 undesirable. A clry non-coking coal, high in carbon, with sufficient 

 volatile matter to kindle it quickly; one with but little or no sul- 

 phur and a low percentage of ash, affords the most desirable coal 

 for domestic use. 



It has been said that the story of the formation of coal is both 

 instructive and interesting and, if that be so, the story of and the 

 methods of obtaining the valuable products to be derived from bitum- 

 inous coal, through destructive distillation, are equally, if not more 

 so and it reads more like a romance than a cold recital of facts. By 

 destructive distillation is meant the process of heating an organic 

 compound in a closed vessel without access of air and the collection 

 of its products. If bituminous coal be placed in a closed retort and 

 heated, there results from such heating four principal products: gas, 

 water liquid, coal-tar and coke. The gas thus formed is not yet fit 

 for illuminating purposes, but must be purified. In the course of 

 this purification, the gases are passed into a tank nearly filled with 

 water and from them, the ammonia, produced by the combination of 

 hydrogen and nitrogen evolved, is rapidly absorbed. This then is the 

 gas or ammonical liquor which is the principal source from which 

 ammonia is derived. If the gas liquor be heated with lime and paised 

 through diluted sulphuric acid, we obtain crystals of Sulphate of 

 Ammonia, so valuable as a fertilizer. 



There are many other products of industrial value associated with 

 ammonia. Much of the gas liquor of gas works is sold to chemical 

 works, yet much is still permitted to waste. 



Coal Tar 



This product of the destructive distillation of coal was once too, 

 like the gas liquor permitted to go to waste, as there was little or 

 no demand for it. Its value, however, has long since been known. 

 From this ill-smelling, to many, a disgusting and unattractive mass, 

 there are today prepared more than six hundred products. Among 

 these are the almost endless varieties of aniline dyes, paraffin, naptha, 

 benzol, anthracene, pitch, napthaline, carbolic acid, creasote, picric 

 acid, and many additional surgical and medicinal preparations. 



WASTES 



When we view the black dense smoke belching forth from chim- 

 neys, the stacks of mills, factories and locomotives, we are reminded 

 that the waste must be, in the aggregate, enormous. In London, 

 where estimates have been carefully made, the loss of coal in smoke 

 when burned in open grates is between one (1) and three (3) per 



