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perheated steam was passed into the vessel at a temperature of 

 from 160 to 250 centigrade. At the lower temperature grease 

 began to distil over, and was deposited on the surface of the hot 

 water as an exceedingly voluminous snow-like mass. This was pe- 

 riodically scooped off and brought to the liquid condition by boiling 

 up with a drop or two of dilute sulphuric acid. The liquid fatty 

 acid on cooling solidified into a hard compact mass, attached to 

 which on the under side was a layer of " foots." The quantity of 

 " foots " seemed to depend upon various factors, such as the amount 

 of dust in the retort, the temperature of distillation and the rate 

 at which steam is sent through the sludge. In the same way the 

 colour of the fat, which ranges from almost white to a reddish brown, 

 seemed to depend upon these same factors, as well as upon the 

 quantity of acid used in acidifying the sludge. The amount of 

 stearic acid and allied bodies thus obtained varied from 7 to n 

 per cent of the original dried material. Determination of the sa- 

 ponification value indicated that the product contained from 88 to 

 97 V 2 per cent of stearic acid Different samples were valued by 

 various grease distillers and soap manufacturers between the limits 

 of 12 and 20 per ton. 



The residue in the retort was found to have lost from 10 to 18 

 per cent of its original weight. The material burns easily with a 

 long white flame; it is easily friable, and absorbent of water. The 

 percentage of nitrogen closely approximates to the percentage in the 

 original sludge, viz., from 1.7 to 3 per cent. The chemical com- 

 position and physical properties of this material indicate that it 

 should have a value as manure. Comparative tests were made on 

 a small scale to determine the difference in weight between vege- 

 tables grown in soils with and without the application of this ma- 

 terial, the conditions being otherwise comparable. With carrots 

 there was an increase in weight of 15 per cent., with beetroot of 

 25 per cent, and with potatoes of 18 per cent. 



It is pointed out that to get the best yield of grease from sludge 

 it is necessary that the sludge for this purpose should be obtained 

 as far as possible in dry weather; the presence of storm water 

 increases the percentage of useless mineral matter. 



The writer suggests that the dry acidified sludge might suitably 

 be distilled in a gas-producer so designed that the upper portion 

 could be subjected to steam distillation alone, while the lower of 

 two exits would take away the gases, formed by the combined action 





