GERBER METHOD. 229 



have been adopted. The use of hydrochloric acid as a solvent 

 for the amyl alcohol has been, however, discarded, following 

 Paterson. 



Gerber employs a test bottle, which he terms an " acido- 

 butyrometer," which difEers from that employed by Lefimann 

 and Beam ; it is a modified form of Marchand's lacto-butyrometer, 

 and, like this, is closed with a cork. 



A definite strength of sulphuric acid is prescribed (90 to 91 

 per cent.), and rules for testing the acid and amyl alcohol used 

 are laid down. 



Gerber has shown considerable ingenuity in adapting the 

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

 method is reliable. 



The following comparative statement will show the difierences 

 •of detail between this and the Leffmann-Beam method : — 



Lefkman.n-Ukam. Gerber. 



). Test bottles are fiasked-shaped. Test bottles are butyrometershaped 



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



used. used. 



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



hydrooliloric acid employed. 



4. Fut read off cold. Fat read off at 60' to 70° C. 



5. Bottles arc 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 Hugershofi'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. 



