BLICHFELDT-GILMOUR METHOD. 



251 



A more simple formula, which gives nearly as good results, is 



T* K - (0-1 P + 0-24) 

 0-244 



The analytical work on which the above formulae are based 

 is due to Eevis and Bolton, the calculations alone being the 

 work of the author. 



The Blichfeldt-Gilmour Method. 



Twenty grammes of the clear filtered fat are saponified in a 

 300 c.c. resistance conical flask with 30 grammes of glycerol 

 and 8 c.c. of 50 per cent, aqueous caustic potash ; a Jew small 

 pieces of porous porcelain are also added. 

 The heating can be done over a naked 

 Bunsen flame. The soap is made up to 

 200 c.c. with distilled water. To 50 c.c. 

 are added 100 c.c. of a solution of sulphuric 

 acid containing 12 '5 grammes of concen- 

 trated acid per litre, and O'l gramme of 

 pumice powder that has been sifted 

 through butter muslin. 



The distillation is carried out in the 

 Blichfeldt distillation apparatus shown in 

 the diagram, which is calibrated to hold 

 100 grammes of water at 55 C., the source 

 of heat being an electric heater regulated 

 to distil to the mark in about twenty 

 minutes. When the distillate has been 

 collected, the apparatus is disconnected, 

 and 0'5 c.c. of 1 per cent, phenol-phthalein 



N 

 and --x NaOH (a few c.c. in excess of that 



which is necessary to neutralise all the 

 acids in the distillate) are added through 

 the condenser tube. The openings are 

 corked and the contents well shaken. At 

 the commencement of the shaking the 

 cork is temporarily released to reduce the 

 pressure inside. The contents are then 

 removed to a 200 c.c. measuring flask and 

 cooled to about 15 C. The excess of 



N 

 alkali is titrated with r^ H 2 S0 4 , and the 



N 



10 



Fig. 34A. 



number of c.c. of r-: NaOH, equivalent to the total volatile acids, 



