GERBER BUTTER TEST. 149 



about two minutes, in order to bring all the liquid into the bulb ; 

 the level of the acid (at as near 60 F. (15-5 C.) as possible) is 

 read off on the graduated scale. About 24 to 3 grammes of 

 butter are weighed into the cup, and after the cork has been 

 inserted, the butyrometer is stood in the water-bath at 60 to 

 70 C. (say 150 to 160 F.) to melt the butter ; when this has 

 been accomplished, the whole is shaken well till the contents 

 form a uniform emulsion ; after standing for a minute in the 

 water-bath, the butyrometer is placed in the machine, and 

 whirled three times, warming in the water-bath for about two 

 minutes between each ; after the third whirling, it is cooled to 

 as near 60 F. as possible, and the level of the aqueous liquid 

 where it joins the fatty layer is read off. The difference between 

 this reading and the level of the acid will give the percentage of 

 water if exactly 3 grammes of butter have been taken ; should 

 any other weight have been taken it is necessary to multiply 

 the result by 3 and divide by the weight taken ; thus, in an 

 experiment 2-780 grammes of butter were taken, the level of 

 the acid was 2-5 and the level of the aqueous liquid 14 '5 ; the 

 percentage of water indicated is, therefore, 



(14-5- 2-5) X 3 12 x 3 



2 . 78Q ; 2 . 78(J = 1 2 '9-5 Per cent, water. 



For the convenience of weighing out the cream, butter, etc., 

 in the cups, a balance of the steel-yard type can be obtained with 

 the machine ; it consists of a beam, with suitable supports, one 

 end of which is longer than the other ; from the shorter end, 

 which also carries a pointer, a small wire cradle to support the 

 cup is hung ; the longer end is divided into 10 equal parts, each 

 being indicated by a notch numbered 1 to 10 ; at the end of this 

 is a fine screw carrying a counterpoise, which can be moved 

 backward or forward by screwing round. 



The weighing is accomplished by placing the cup in the cradle, 

 and screwing the counterpoise backward or forward, as required, 

 till the pointer is at zero in the middle of the scale ; the cup is 

 now removed and filled with the product to be tested, and the 

 riders are put on the various notches in the beam in succession 

 till equilibrium is restored. The largest rider indicates grammes, 

 the medium tenths of a gramme, and the smallest hundredths 

 of a gramme. 



Thus if the largest rider is in notch 2, the medium 7, and the 

 smallest 8, the weight is 2-780. 



If it be found that to restore equilibrium it is necessary to 

 place the smallest rider intermediate between two notches, say 

 between 2 and 3, the reading is taken as 0-025. 



If it be found that two riders must be placed on the same 



