78 CALORIFIC POWER OF FUELS. 



or coke formed, this increase is produced gradually by cutting 

 off the lean coals and dividing the fat coals into three classes 

 gas, forge, and coking. 



Bearing on the advisability of having proximate analyses, 

 as well as ultimate analyses of coal, is the question recently 

 brought up by Mr. Kent, regarding the ratio of hydrogen and 

 carbon in coal. In discussing the results of Lord and Haas' 

 determinations of Ohio and Pennsylvania coals, he thought he 

 had discovered the ratio, that the fixed carbon is nearly equal 

 to the total carbon minus five times the available hydrogen in 

 bituminous coals, and minus three times the hydrogen in 

 semi-bituminous ones. He gave a table showing results 

 which support the hypothesis. 



LIGNITE. 



From an industrial standpoint lignite is of considerable 

 importance. It occurs in most countries, and is used in a 

 great many for domestic and manufacturing purposes. 



As a fuel it is inferior to coal, being less distantly 

 removed from woody fibre, and hence contains more hydro- 

 gen and, usually, considerable water. Most of the latter, 

 however, dries out on exposure to the air. In some cases 

 as much as 40 or 50 per cent of water is found in the 

 freshly mined lignite, of which at times 20 per cent remains 

 when air-dried. This greatly affects its value as fuel ; still 

 it is used in many of the Western States, and also in 

 Europe. In some European localities, when thoroughly 

 dried and compressed into blocks, especially in Italy and 

 Austria, it is used as fuel for producing gas and for evapo- 

 rating, with good results. In Austria it is burnt without 

 any preparation, except drying in the air for heating salt- 

 pans. 



The amount of ash varies exceedingly, being in some 

 cases as low as 0.9 per cent, and in others as high as 58 per 



