11 



„a,e. and t„e amount ^ ^^^^^'^i^'^^^ ::^^?^ ^o"^^^ 



each cheese made '"Xrlvinool but enough was done to show the amount 

 :rcL"e?n ^e^d«'e°d "5ub.f ..ionXy' d "ing a 'period o, eleven months. 



Notes on Methods of Analyses. 

 c v,.rr Tn taking the sample for analysis, two plugs were drawn from 



.j:^^. if '- t? ahh^rSo-p'peT u°;t,eTns?drthe''h^o"t.r.t.tr t 

 :'hfn s^^a^I! wei; mii^I'a^d'tiih.'ircor.Tup. ^From this portions were taUen 



for analysis. 



Total Nitroo-enous Matter, (principally casein). The nitrogen as deter- 

 mined by the Kleldahl process', was multipUed by 6.25 to obtam mtrogenous 

 matters. 



Water Soluble Nitrogenous Water. Ten grams of cheese were ground in 

 a porcelain mortar with sharp clean sand, transferred to a ^^^^ treated wt^ 

 from 7S to 100 cc. of cold distilled water, and warmed m a \yater bath to 00 

 to 65 degrees C. as soon as possible. After reachmg this temperatu e 

 and after thorough stirring the liquid was poured on a pad of cotton wool in 

 a glass funnel and filtered into a 500 cc. flask. Another portion of water at 

 abSut 60 degrees C. was then poured on the sand and cheese, and the tlask 

 containing them replaced in a water bath at 60 to 65 degrees L. Ihi^ operation 

 was repeated six or seven times, with frequent stirrings, the water remaining 

 in contact with the cheese from 15 to 30 minutes. Each extraction occupied 

 from two to three hours. The cheese extract thus obtained was cooled ana 

 made up to a volume of 500 cc, and then filtered under pressure through a 

 - thick pad of asbestos. The nitrogenous matter soluble in water was then 

 obtained by determining the nitrogen in an ahquot portion of the extract by 

 the Kjeldahl process, and multiplying it by the factor 6.25. 



Ammonia was determined in the original cheese by grinding a suitable 

 quantity (usually 10 grams) with cold water in a porcelain mortar, transferring 

 to a distillation flask, making alkaline with magnesium oxide (MgO) and dis- 

 tilling off the ammonia. 



It is not, strictly speaking, correct to use the term "casein'' when the total 

 nitrogenous matter is meant; yet, as casein is the principal nitrogenous con- 

 stituent of new cheese and the one best known to dairymen, it will be used in 

 that sense in the discussion of results hereafter given. 



Rate at which Caseix is Changed to Soluble Compouxds. 



The following table gives the average percentage of total casein in A and 

 E cheese found soluble in water at the end of one, two, three, and up to eleven 

 months. The figures do not represent the rate at which the casein in any one 

 pair of cheese became soluble; but the average of all cheese for the season 

 when one, two, three, etc., months ofd. The percentage of total casein changed 

 to ammonia for the same periods is also given. These figures, therefore, repre- 

 sent the averages obtained from cheese one or more months from date of mak- 

 ing at all seasons of the cheese-making year. 



