318 



BUTTER. 



limb of the T piece is opened and turned downwards, and the 

 alcohol distilled ofi during a quarter of an hour ; 100 c.c. of 

 boiling water are added by the T piece, and the flask heated on 

 the water-bath till the soap is dissolved. The solution is allowed 

 to cool to 50° or 60°, 40 c.c. of dilute sulphuric acid (25 c.c. to 

 a litre ; 2 c.c. of soda solution should neutralise about 35 c.c. 

 of this), and two pieces of pumice the size of peas are added. 

 The flask is at once furnished with a cork carrying a tube 07 cm. 



Fig. 43. — Caustic Soda Apparatus. 



in diameter having, 5 cm. above the cork, a bulb 5 cm. in 

 diameter ; above this the tube is bent at an angle of 120°, and 

 5 cm. further on again at an angle of 120° ; this tube is joined to 

 a condenser by an india-rubber tube. The flask is heated by a 

 very small flame till the fatty acids are all melted, and the flame 

 is then turned up and 110 c.c. distilled off in from twenty-eight 

 to thirty-two minutes. The distillate is well mixed, and 100 c.c. 

 are filtered off through a dry filter, 1 c.c. of a 0"05 per cent. 



