358 ANALYSIS OF CHEESE MILK STANDARDS 



Fat. About 5 grammes of the cheese are rubbed up in a mortar 

 with about 10 grammes of anhydrous copper sulphate. The mixture 

 is introduced into a Schleicher & Schiill's filter-paper thimble and ex- 

 tracted with ether for eight or ten hours in a Soxhlet extractor. The 

 ether is then distilled off and the fat weighed. 



Casein. The total nitrogen is determined by the Kjeldahl pro- 

 cess, 1 using about 2 grammes of cheese. The percentage of nitrogen 

 is then multiplied by 6'38 and the product taken as casein. 



These methods are those usually employed, but are not entirely 

 satisfactory. Attempts to differentiate between the products of ripen- 

 ,ing have been made,^ but they are too complicated to be discussed 

 here. 



Milk Standards. The establishment of a standard by which to 

 judge of the quality and freedom or otherwise from adulteration of a 

 sample of milk, has received much attention and consideration. In 

 September, 1901, the Board of Agriculture decided to take 3 per cent 

 of fat and 8*5 per cent of solids-not-fat, as the probable lower limit in 

 the case of genuine milk, and it was enacted by law that if a specimen 

 did not come up to these figures a presumption should be raised that 

 it was not genuine, by reason of the abstraction of fat or the addition 

 of water. While these values are much below the average, and to that 

 extent satisfactory from the producers' point of view, it must be re- 

 membered that with morning milk, when the night interval is much 

 longer than the day one, the fat content of genuine milk may often be 

 below this standard. Indeed, according to the experience of the author 

 during the very dry autumn of 1901, the mixed milk of dairy shorthorn 

 cows in the morning was far more often below than up to this standard. 

 The cows were at pasture, but received 2 Ib. decorticated cotton cake 

 each per day. For evening milk, on the other hand, the standard for 

 fat is very much below the average, and lower, perhaps, than the con- 

 sumer has the right to expect. 



The difficulty of choosing a satisfactory standard is great, and per- 

 haps almost insuperable, when the great differences which are often 

 shown between evening's and morning's milk are taken into account. 

 If cows could be milked at regular intervals of twelve hours each, these 

 differences would be greatly diminished, but unfortunately the exigencies 

 of the trade almost necessitate great inequalities in the intervals be- 

 tween milkings. A different standard f o morning and for evening 

 milk would, perhaps, better meet the case ; but, in practice, difficulties 

 in administering the law would arise. 



1 Vide p. 85. a Vide Chap. XV. 



