BUTTNER AND MEYER DRYER. 181 



revolve, forcing the cossettes to move forward and projecting 

 them from one compartment to another through the openings 

 that are arranged in the separating division. These passages 

 are not in each case in the same position, and under these cir- 

 cumstances the gases and cossettes are forced to take a zig-zag 

 motion in passing through the apparatus. In this dryer, as in 

 the appliance already described, the gases move in the same 

 direction as the cossettes, but they leave them before reaching 

 the last compartment of the apparatus, from which they are 

 drawn off by a ventilator, F, which forces them to first pass 

 through the so-called " cyclones," C, and then into the channel, 

 K, placed beneath the last heating chamber, which receives its 

 caloric indirectly, L e., without danger of burning the cossettes. 

 But they leave this last compartment to fall ultimately thor- 

 oughly dried into the spiral, S. It is important to rectify a 

 very erroneous assertion advanced by the inventors of this 

 dryer. They claim that the gases on leaving the division before 

 their final exit, heat the last chamber, and thus allow the 

 utilization of the latent heat of water evaporation held in sus- . 

 pension by the circulating gases. This is an erroneous theory; 

 as it is impossible for water evaporated from the cossettes to 

 become re-heated to any considerable extent so as to be again 

 utilized for future work. From the very time that water has 

 passed into the condition of steam it becomes an inert gas, 

 which mixes with the hot gases and can no longer condense in 

 transmitting its heat to the cossettes, unless the residuum, for 

 one reason or another, has become cooled at the very time that 

 the water evaporated was liberated, and there is no possible 

 reason for such cooling. Experiments show that 2,539 kilos of 

 coke are needed to dry 21,000 kilos of cossettes in twenty-four 

 hours. One man can attend to an apparatus of 100 tons 

 capacity per diem. 



Notwithstanding the numerous efforts made to solve this Buttner and 

 problem, from an economical standpoint, the Buttner and ^ tr dr y er - 

 Meyer dryer actually holds its own to-day against all comers, 

 mainly from a practical point of view. 



The Buttner & Meyer furnace is based upon two principles, 

 one of which is that the hot gases from the center of combustion 



