112 MANUAL OF GENEKAL AGKICULTURE. 



84. DETERMINATION OF SALT IN BUTTER. 



Materials: Burette with stopcock, white cup, sat- 

 urated solution of potassium dichroraate, silver nitrate 

 solution made by adding 14.531 grams of silver nitrate to 

 1000 c.c. of distilled water. Butter to be tested, small bot- 

 tle with cork or cover, 250 c.c. Florence flask with the 

 250 c.c. height marked with a file. 



Melt about two ounces by guess of butter in a small 

 covered bottle as was done in testing for moisture. Weigh 

 into the Florence flask exactly ten grams of the melted 

 sample, then add enough rain water of a temperature of 

 about 140 F. to make 250 c.c. Shake thoroughly several 

 times to dissolve the salt. Take 25 c.c. (best obtained 

 with a 25 c.c. pipette) of the brine solution thus prepared, 

 place it in the cup and add 2 or 3 drops of potassium 

 dichromate as an indicator. 



Place the silver nitrate solution in a bruette arranged 

 as in testing for the acidity of milk. Gradually let it run 

 into the cup until a permanent pink color remains upon 

 being thoroughly stirred. Note the number of c.c. of sil- 

 ver nitrate used. Divide this number by the factor 2. The 

 result is the per cent of salt in the sample. As salt is much 

 cheaper than butter fat it is to the advantage of the butter 

 maker to add about as much as the market will bear. 

 Three per cent may not be too much. 



85. DETERMINATION OF THE PER CENT OF FAT 

 IN ICE CREAM. 



Materials: Glacial acetic acid, sulphuric acid, ice 

 cream, Babcock tester, and milk test bottle. 



Weigh nine grams of the melted sample into a Bab- 

 cock milk bottle. Fill almost to the neck with a mixture 

 of glacial acetic acid and sulphuric acid, using equal vol- 

 umes of each. Heat a few minutes until black, then whirl 

 in the tester for five minutes. Add water to bring the fat 

 column within the graduation of the neck as in the regu- 

 lar Babcock test. The reading multiplied by two gives the 

 per cent of fat in the ice cream since the bottle is gradu- 

 ated for 18 grams and only 9 grams were used. 



