10 BULLETIN 921, U. S. DEPARTMENT OF AGRICULTURE. 



The increased cost of operating the clarifying department of a 

 sirup factory of 50 tons daily capacity, using infusorial earth and 

 the above equipment, in comparison with the skimming method, may 

 be estimated as follows : 



Cost of infusorial earth delivered, 11 pounds per ton of cane, 



or 550 pounds, at 2 cents per pound $11 



Extra labor— one man each shift, at $2.50 5 



16 2 



The total increased cost per ton, assuming an operating period of 

 60 days, or a total tonnage ground of 3,000 tons, can be estimated 

 as follows : 



Cents.. 



Interest on investment, at 6 per cent $102-^3,000= 3.4 



Depreciation, 10 per cent of investment 170-^3,000= 5.6 



Filter cloths 80-^3,000= 2.6 



Infusorial earth and extra operating expenses, 

 as per above 32.0 



Total, per ton 43.6 



It is necessary now to show what financial advantages result from 

 making sirup by this infusorial earth and filter press method to 

 offset this apparent appreciable increase in cost. The outstanding 

 feature is that no skimmings are obtained. Ordinarily, in a factory 

 of this capacity, from 2,000 to 4,000 pounds of skimmings per day 

 will be thrown away or fed to the hogs. These skimmings, with an 

 average sugar content of 10 per cent, show a loss of 200 to 400 pounds 

 of sugar. Figuring 8 pounds of sugar to the gallon of sirup, in 

 grinding 50 tons of cane, from 25 to 50 gallons of sirup are lost. 



In the above experiments on filtering the whole juice with infu- 

 sorial earth, the resulting press cake from 6 tons of cane averaged 

 275 pounds weight with a sugar content of 6 per cent. From 50 

 tons of cane about 2,291 pounds of press cake would be obtained, 

 which with 6 per cent sugar would give 137 pounds of sugar lost, 

 or only 17 gallons of sirup per 50 tons. However, this loss can be 

 reduced further. The press cake that is formed is very porous and 

 is washed easily. Twenty gallons of water per ton of cane will 

 easily reduce the sugar content of the press cake to 1 per cent, in 

 which case the loss on 50 tons would be about 23 pounds of sugar, or 

 about 3 gallons of sirup. 



If a value of $1 per gallon is assumed for sirup, the saving in 

 items of dollars and cents on 50 tons of cane can be calculated as 

 follows : 



Loss by skimming process, 25 to 50 gallons of sirup, or $25 to $50. 

 Loss in the infusorial earth clarification process when the cake is not 

 washed, 17 gallons of si nip, or $17. 



2 Or 32 cents per ton. 



