H2 CHEMICAL FERTILIZERS 



distils out, and carries with it much of the water vapour. 

 By these means the water content can be lowered to the 

 desired extent. After the mateiial has become sufficiently 

 dried and mixed up with benzine, the whole apparatus is 

 allowed to rest : the benzine, which rises to the top, is 

 run off by a side cock and pumped up to the steam-heated 

 still, where the benzine is driven off, leaving behind the oil 

 which has been extracted from the fish. The benzine is 

 used over and over again. About three extractions are as 

 much as it is practicable to give, and if 600 gallons of benzine 

 are put into the boiler, about 400 gallons can be removed 

 each time. Considerable quantities of benzine are left 

 with the fish residue, but are distilled out with steam, 

 which is admitted to the interior, and helps to drive out the 

 benzine ; as a vacuum is maintained all the time, very 

 little steam need be admitted to the interior of the plant. 

 Great ingenuity is exercised in reducing the loss of benzine, 

 which has been so successfully conserved that only 

 about | % of the benzine is lost at each extraction. A 

 5-ton charge of half-cooked fish refuse yields about 

 25 cwts. of fish manure, but this varies somewhat with the 

 seasons : June and July herring guts give 5 cwts. of fish 

 manure from each 30 cwts. of refuse. The dried and ex- 

 tracted fish manure is removed by a door at the end of the 

 cylindrical boiler, and at once put into sacks. Sometimes, 

 after removal from the cylinder the material is ground, 

 passed over an electro-magnetic roller to remove any fish 

 hooks, nails and other iron objects which it might con- 

 tain, and made to pass through a J-inch riddle. 



The dust and fumes arising from this manufacture 

 cause considerable difficulty and annoyance. The waste 

 gases coming from the cooking plant are sent up flues and 

 washed with water, the water running to waste. From the 

 grinding mills where the dry material is ground up, a fan 

 must be kept running to draw the fine fish meal away, which 

 otherwise would cause a great annoyance to the workmen. 

 The material is sucked away from the grinding mills in a 

 very fine dusty condition, but can be separated by means 



