80 CALORIFIC POWER OF FUELS. 



Scotch Boghead generally contains 18 to 24 per cent of 

 ash. From its analysis as above, its heat of combustion 

 should be near that of the other one given. 



PEAT. 



Peat is formed by the agglomeration of vegetable cttbris+ 

 and retains a large amount of water, which will not separate 

 without heat. Its composition varies but little from that of 

 wood, the principal difference being less oxygen and more 

 carbon. 



The composition may be represented by 



Carbon 60 



Hydrogen 6 



Oxygen and nitrogen 34 



100 



The heat of combustion is lower than that of coal or 

 lignite, as might be expected. The quantity of hydrogen 

 exceeds that necessary to form water with the oxygen. 



It is usually dried before using, and when dry becomes 

 quite porous. It carries, however, in this state some 10 to 

 15 per cent of water, which can be expelled only by artificial 

 means. Large quantities of it are converted into charcoal in 

 special kilns, and, where the large amount of ash is no objec- 

 tion, it makes a good fuel. It cannot be used for metallurgical 

 purposes on account of its friability. From 30 to 40 per 

 cent of its weight is left in the charcoal as carbon, but at the 

 same time the ash increases to 15 to 25 per cent, and even 

 more. This consists principally of phosphates and sulphates, 

 with very little carbonates ; hence it is not as apt to clinker 

 as other fuel ashes. 



Brix obtained with peat an evaporative power of 5.11 

 pounds of water. The peat used was from Flatow, and 

 contained 10.7 percent of ash. Another, from Buchfeld-Neu- 

 langen, contained 1.2 per cent of ash, and gave 5.12 pounds 



