LEFFMANN-BEAII METHOD. 223 



bottles are nearly, but not quite, radial. Tbis position is advan- 

 tageous, as it allows of tbe most rapid separation of tbe fat from 

 tbe acid liquid. 



Apparatus. — Tbe test bottles consist of flat-bottomed flasks 

 with a sloping upper portion terminating in a graduated neck. 

 Tbe bottles (Englisb make) bold 29 c.c. ; tbe necks are made of 

 glass tube 5*96 mm. in internal diameter, and are so graduated 

 tbat 80 divisions = r475 c.c. Tbese dimensions are according 

 to a specification laid down by tbe autbor, and differ sligbtly from 

 tbose prescribed by Leffmann and Beam. Tbe pipettes used are — 



15 c.c. for milk, 

 9 c.c. for sulpburic acid, 

 3 c.c. for amyl alcobol mixture, 

 4*5 c.c. for cream, and 

 10"5 c.c. for water. 



Automatic measuring apparatus and burettes may be also used 

 for measuring tbe acid and amyl alcobol. 



Tbe autbor bas devised a burette specially for tbe measure- 

 ment of sulpburic acid and otber corrosive liquids. It has been 

 found, in practice, tbat ordinary burettes are liable to be filled 

 to overflowing, and tbat considerable inconvenience is caused by 

 spilling strong sulphuric acid. 



An ordinary burette with a three-way tap is used, and to tbe 

 tube, for fiUing from the bottom, a wider tube, ^ inch in diameter 

 and 3 inches long, is fused. An india-rubber cork is inserted in 

 this, and through it is passed a long glass tube bent as a syphon, 

 which serves to convey the acid from a stock bottle above. 



In tbe top of the burette an india-rubber cork is fixed, through 

 which passes a tube going almost to the top of an air chamber of 

 glass ; to tbe bottom of tbe air chamber a glass tube of small 

 bore passes upwards so far as just to enter into tbe stock bottle. 



Tbe illustration (Fig. 23) will make the construction clear. 



Tbe conditions necessary for satisfactory working are : — 



1. Tbe capacity of air chamber and tube leading to stock 

 bottle must not be more than i of tbe capacity of the burette. 



2. The bottom of the stock bottle must be well above tbe top 

 of the tube leading into tbe air chamber. 



The tube leading into the air chamber must be adjusted to the 

 mark on the burette equal to its capacity. 



The burette is used as follows : — The tap is turned so that 

 tbe liquid enters and fills tbe burette. As it reaches the upper 

 portion, it passes up the tube and overflows into tbe air chamber, 

 from which it is forced up the tube leading to tbe stock bottle. 

 When the liquid reaches a height corresponding to tbe level of 

 the liquid in the stock bottle, the liquid ceases to run, and the 



