GERBER METHOD. 139 



Gerber has shown considerable ingenuity in adapting the 

 method of Marchand to that of Leffmann and Beam, and the 

 method is reliable. 



The following comparative statement will show the differences 

 of detail between this and the Leffmann-Beam method : 



LEFFMANN-BEAM. GERBEE. 



1 Test bottles are flask-shaped. Test bottles are butyrometer-shaped. 



2. 96 per cent, sulphuric acid is 90 to 91 per cent, sulphuric acid is 



used. used. 



3. A mixture of amyl alcohol and Amyl alcohol alone employed. 



hydrochloric acid employed. 



4. Fat read off cold. Fat read off at 60 to 70 C. 



5. Bottles are used open. Bottles are stoppered. 



There is no practical advantage in either method. The original 

 Leffmann-Beam is somewhat more rapid, while the Gerber modi- 

 fication requires rather less skill. Both are equally accurate. 



I. The Tester with Catgut Action for Four and Eight 

 Samples (Gaertner and Hugershoff's Patent) Description. 

 A steel spindle, running in two ball bearings, the upper with ten 

 balls and the lower with seven, is supported in a well -stayed 

 frame, which can be fixed to any table by means of a screw 

 clamp. On top of the spindle is a boss, on which two discs with 

 screw, threads are fastened, which hold the disc-plate for the 

 reception of four or eight samples. The cover is screwed on to 

 the spindle by means of a loose milled-headed nut and the machine 

 is ready for use. If the machine is destined for frequent use, 

 it will be best to fix it to a strong bench and not to a movable 

 table ; to strengthen it further, two screws may be put in through 

 the holes in the frame and the tester will then not be transportable. 



The bearings can be adjusted by means of the brass collar in 

 the upper one which is held in place by two screws ; this should 

 be so arranged that the spindle runs easily without play, and 

 when this is found to be the case, the screws should be tightened 

 to hold the collar in place. The bearings should be oiled with 

 good machine oil, care being taken that the oil which runs down 

 the spindle is wiped off. 



To rotate the machine, put the metal end of the catgut into 

 the hole in the spindle, wind the string around, by turning the 

 disc-plate backwards till the handle is close to the spindle. Pull 

 the handle with full strength, the whole weight of the body being 

 brought to bear, and as the string unwinds the machine is rotated ; 

 when all the string is unwound the end comes out of the hole, 

 and the machine rotates freely. If clean and well oiled it will 

 run for ten minutes. 



To stop the machine, take hold of the milled-headed nut of 

 cover firmly and it will screw itself off ; then press the edge of 



