Tlir Vi!<cotiity of Cream. iiOU 



Foll()\viii<,f a su<4gvsti(iu made by Mr. P. Denstoi], dairy clieinist 

 to tlie Bacfluis Marsh Dairy Co.. it is proposed to speak of this 

 aciditv as the " critit;il acidity," and it can be shown that, for 

 fre.shly-.separated creaiu, the critical acidity of the cream serum is 

 apparently a constant, independent of fat content. For example, 

 if several samples of cream, differing in fat content be gradually 

 acidified, there Mill jje in each case a definite degree of acidity, at 

 which the viscosity (which at first rises by barely perceptil)l(? 

 amounts with small im-roasc-s of acidity) suddenly increases very 

 considerably upon the least further addition of acid. This is the 

 critical point. The critical acidities in terms of the full cream 

 have difleient values for \\\v different samples, varying witli tlic fat 

 content. The fat is, however, an inert, suspended material, and 

 if the critical acidities ])e recalculated for the cream minus fat — 

 i.e., for the cream seium, they will be found to have appioximately 

 the same values. 



The following expeiinieiits i'<mfirm this statement : — 



TAIUJ-: I. 



Cream separjited from new milk, and soured l)y addition 

 (»f pure lactic acid. 



.^(•i(lit> ill cc. of 



,. . , Time nf flow . N l'";it coiitfiit. 



KxpcTnnei.t. (s^.-o.-ls) NaOll,„l.er 100 cc. (,h..- cent.) 



of civaiii sernni. 



A - L'40 - lO.f) - 4l> 



:345 .■)4.9 - — 



108") - o6.sr. - — 



B - 170 lit. 07 - .",9 



187 - 45.0 - — 



200 - r)i.r. 



2-jr) - .-)4.! - — 



3G0 - 57.2 



c - 10." - 15.G - r,r. 



108 - 4:5.7") - — 



13G - r)(i.2.") - _ 



560 - 57.8 - — 



720 - 68.75 - — 



I) - 57.5 . 17.53 - 23 



67 - 50.65 - — 



105 - 54.54 - — 



155 - 55.84 - — 



285 - 61 - — 



345 - 63.6 - — 



