MANUFACTURE OF BONE SUPERPHOSPHATE. 183 



ing it through the condenser C, by means of the gooseneck 13, and 

 the tap 21: ; it goes to the reservoir E. The benzine impregnating 

 the bones is subjected to a current of steam, which finishes by en- 

 training it into the distilling apparatus. When it has been made 

 certain that nothing but water passes in the distillate, the extractor 

 is emptied, first opening the lid of the top manhole, and then the 



Fig. 36.— Plant for Extraction of Fat from Bones by Petroleum Benzine. 



bottom one. The distillation is urged until no more petroleum 

 benzine distils. At this moment a current of steam is injected into 

 the fat by means of a perforated steam coil which carries off the last 

 traces of solvent. The fat can then be drawn off from the distilling 

 pan by the tap 21. ^; ' 



Purification of Bone Fa^.— Fresh bone fat is naturally whiter 



