478 ADDENDA. 



Thus, if the specific gravity of a sample of cream is 1-0035 

 or 3-5 degrees, the fat is 32-5 3-5 x 0-91. Multiply 3-5 by 

 0*91 on the slide rule and subtract from 32-5. 



P. 370. To calculate the percentage of fat in the milk or cream from which 

 cheese of any given percentage of fat and protein was made. 

 Let P = protein, and F = fat in cheese, and F 1 = fat in 

 milk, then 



1 _ 0-354 P 



F 1 0-25 ~ F 



Place cursor against P on lower scale, bring F against it, 

 and bring the cursor against 3-54, add on 0-1 to the lower 

 scale, move the cursor to this. Next bring 10 or 1 against the 

 cursor, and the value of F 1 0*25 is on the scale on the slide 

 against 10 or 1 (multiply by 10 if 1 were used). Add on 0-25 

 to this, and the answer will be the percentage of fat in the 

 milk. It may happen (in cream cheeses only) that 35-4 lies 

 off the scale, in which case the cursor must be placed against 1, 

 and then 10 brought to the cursor ; then 0-01 must be added, 

 and not 0-1. 



If the value of F 1 0-25 lies against 1 and not against 10, 

 multiply the value by 10, but be careful only to add 0-25. 

 By reversing the slide, logarithms can be read to two places 

 on the total solids and solids not fat scales, and estimated to 

 three. Place 1 against 5 on the T.S. scale, subtract 5 from the 

 reading, and divide by 10. 



P. 211. Hydrogen peroxide may be detected in pasteurised milk by adding 

 about 10 per cent, of the , volume of the milk of a maceration 

 of peeled potato in water, and testing with ortol or para- 

 phenylene-diamine. This test is due to Fouassier. 



P. 231. The aldehyde figure (p. 182) may be determined on 25 c.c. of the 

 water soluble extract, and the ratio of this to the total soluble 

 extract will give an expression of the ripening. This is a modi- 

 fication of Geake's method of estimating the degree of ripeness 

 of cheese, which consists in grinding up 8 grammes of the cheese 

 three times with 30 c.c. of acetone, and allowing the residue 

 to dry in air. Three grammes of this residue are shaken with 

 50 c.c. N/10 caustic potash for one hour, and the mixture 

 filtered ; 20 c.c. of the filtrate are neutralised to phenol-phthalein 

 with N/10 sulphuric acid, and again after the addition of 10 c.c. 

 of neutral formaldehyde solution. The total nitrogen is deter- 

 mined in 5 c.c. of the solution. The aldehyde titration is 

 calculated to amino -nitrogen, and this is expressed as a per- 

 centage of the total nitrogen, the figure being higher the riper 

 the cheese. 



P. 299. (Cf. also p. 183.) Abnormal milks low in acidity are, according 

 to Van Slyke and Baker low in specific gravity, total solids, 

 fat, milk-sugar, and casein, but high in other proteins, ash, 

 and chlorine. This is in general agreement with the author's 

 observations. 



P. 64. They also find that large numbers of leucocytes are often present 

 in milks of low acidity, and the composition of abnormal 

 milks agrees with the view that blood serum or lymph is 

 present. 



