228 THE CHEMICAL CONTROL OP THE DAIRY. 



Testing of Clotted Cream, Cheese, and Butter.— Weigh 

 the bottle and transfer to it about 1 to 1-5 gramme of butter, 

 2 grammes of clotted cream or 3 grammes of cheese, and weigh 

 again. Butter should be melted in a closed vessel at a tempera- 

 ture of 40° C. (104° ¥.), and, after shaking, about IJ c.c. sucked 

 up in a tube which will just enter the neck of the bottle ; the 

 butter should be blown in as completely as possible. Clotted 

 cream should be well mixed and sucked up in a tube in the same 

 way as butter, and either blown or pushed in with a wire. Cheese 

 should be cut up into small pieces, which can be dropped in. 

 Add sufficient water to make up the weight to 15 "25 grammes- 

 and proceed as in analysing milk. Cheese requires rather longer 

 shaking than other products, but gives equally good results. 



If desired, cream may be weighed instead of being measured. 



The calculation is performed as for sour milk. 



The above directions diSer in some respects from those giveu 

 by Lefimann and Beam. The author has had, however, some 

 years practical experience of the methods described and is con- 

 vinced of their accuracy. A stand for the bottles is to be 

 recommended ; this may conveniently be made of wire rings 

 into which the bottles fit, with a flat plate for a bottom ; the 

 bottles can then be easily carried about. 



To clean the bottles : empty while hot in a convenient recep- 

 tacle, and wash twice thoroughly with hot water ; if necessary, 

 run a brush down the neck. They are conveniently washed in 

 the stand. Never leave pipettes dirty. 



Failures and their Probable Causes. — The only failures 

 likely to happen are : — 



1. Dark layer of fat. 



2. FlufEy layer under the fat. 



1. If the acid be too strong, or the temperature too high, or 

 the mixture left too long before whirling, the fat may be dark. 

 The remedy is obvious. 



2. A fluffy layer under the fat is often caused by allowing the 

 milk and acid to stand too long unmixed. It may sometimes be 

 due to a bad quality of amyl alcohol. 



Grit on the bottom of the bottles may cause fracture while 

 in the machine. Fracture may also occur from too sudden a 

 stoppage after the whirling is completed. 



Modifications of the LefiFmann-Beam Method. — The 

 Leffmann-Beam method has been subjected to considerable 

 modification ; thus Paterson and, later, Gerber have used amyl 

 alcohol alone without hydrochloric acid. 



Gerber's Aeido-butyrometric Method.— This is essentially 

 the Lefimann-Beam method, the chemical principles of which 



