86 



CALORIFIC POWER OF FUELS. 



Gottlieb obtained the following numbers, using a calo- 

 rimeter of constant pressure, in which he burnt 2 grams of 

 wood in the space of two or three minutes. The composition 

 of the gas produced was not determined ; he was satisfied 

 that he had perfect combustion, and his figures do not appear 

 very far from the truth. For cellulose he obtained 41 5 S 

 calories. 



Gottlieb's results are 69 calories less than Mahler's for oak 

 and 207 more for fir. 



In burning wood for steaming the fire is easily controlled ; 

 combustion is more complete ; the products of combustion 

 contain only very small quantities of unburnt gases ; and the 

 ashes are generally free from carbon. The countries using 

 wood for this purpose are growing less in number yearly, on 

 account of improvement in transportation and the discovery 

 of new coal seams ; petroleum oils for fuel have also become 

 more common, especially in Russia, the United States, and 

 Canada. 



Morin and Tresca, in their tests, found that one pound 

 of wood was equivalent to 0.368 pound of coal. Scheurer- 

 Kestner's experiments in 1871 show results more favorable 

 for wood. The wood used was Vosges fir, which had been 

 piled under cover for half a year. A cubic foot weighed 

 19.76 Ibs. It was burnt in the same boiler used in his 

 previous experiments, with the result that I pound of wood 

 evaporated 4.4 pounds of water. The ratio was 0.490, or 

 nearly one half that of Ronchamp coal. 



