FUELS AND THEIR UTILIZATION. 43 



gas of four candle-power from ten pounds of tar by injecting the tar into the 

 highly heated retorts and thereby hastening the process. With a slow flow 

 of tar into the heated retorts they increased the lighting power of the gas to 

 eight candle-power, but lessened the quantity produced. By this method ten 

 pounds of tar furnished sixty cubic feet of illuminating gas of eight candle- 

 power. This process was practically tested and is highly recommended by a 

 number of factories and smelting establishments after many years use. 



More recently very satisfactory results have been obtained in the manufac- 

 ture of illuminating gas from brown coal by treating it with paramne oil. 

 The materials have to be well mixed, and after a few days standing it will be 

 found that the lignite has completely absorbed the oil, and is then ready for 

 transportation. The coal prepared in this way furnishes an illuminating gas 

 of excellent quality, and can be used in common stone coal retorts. 



DYES. 



The manufacture of the so-called tar colors, analine, etc., has become of the 

 highest economic importance, but as it constitutes an independent industry it 

 must suffice in this place to notice that lignite tar has been largely and suc- 

 cessfully used in color factories. The attention of manufacturers was early 

 called to the fact that the tar obtained from the distillation of brown coal was, 

 in its constituent parts, very similar to stone coal tar; and A. C. Lieberman 

 and 0. Burg showed that the tar conducted through heated tubes filled with 

 charcoal changed into a mixture of hydro-carbon, containing, like stone coal 

 tar, four per cent of benzol and toluol and nine-tenths per cent of raw an- 

 thracen, and generally very much resembled the stone coal tar used in the 

 manufacture of dyes. The results have been fully satisfactory. 



LAMP BLACK. 



The manufacture of blacking powder from brown coal deserves mention. 

 Kramer described the process of its manufacture in 1855, and mentioned es- 

 pecially the superiority the product possesses over the bone black then in use. 

 He states its price to be half of that of bone black by superior covering quality, 

 and not requiring, like the former, an addition of sulphuric acid. F. Matthey 

 and others have more recently treated the subject. 



TANNING MATERIAL. 



In order to use brown coal for tanning purposes, W. Skey heats the coal 

 with nitric acid and evaporates the mixture to dryness. The dark brown 

 residue dissolves in water, possesses a bitter, astringent taste, and precipitates 

 lime from water solutions. 



