LEFFIIAXX-BEAM METHOD. 



^27 



mixture can be measured. If the cream is sour a few drops of 

 ammonia should be placed in the pot before the weights of water 

 and cream are adjusted. 



The measurement is performed as follows : — Fill the pipette 

 with cream by sucking at the top, and close it with the finger ; 

 hold the pipette vertically, and allow the cream to run down 

 till the upper surface is on a level with the mark ; turn the 

 pipette to a horizontal position and wipe the stem ; then return 

 it to the vertical and, holding the point over the neck of a test 

 bottle, allow the cream to run out freely ; after the quick succes- 

 sion of drops has ceased allow three more drops to run. Add 

 10'5 c.c. of water and proceed as in analysing milk. 



Calculate the results from Table LX., using column 3 for 

 undiluted cream and column 2 for diluted cream. This table 

 should be checked by gravimetric analysis whenever a new 

 pipette is used. 



TABLE LX. — For Estimating Fat in Cream. 



Testing of Sour Milk.— Weigh in a small beaker about 

 15 jrranunos of the sample which has been previously well mixed 

 by whisking with a brush formed of fine wires ; pour as much 

 as possible into a test bottle and re-weigh the beaker ; the difier- 

 eiKO will give the weight of the milk taken : add sufficient water 

 to make up to ir)-25 L'rarames and proceed as in analysing milk. 



Calculate as follows : — Multiply the reading by 15-25 and 

 dividi' by the weight taken : the result will be the percentage 

 •of fat in the sour milk. 



