180 EXPERIMENT STATION RECORD. 



The "serum difference 1 ' of butter serum was found to average as 

 follows : In sweet-cream butter 50 per cent, in sour cream butter 45 per 

 cent; or, 8.45 and 8.16 parts per 100 parts of sweet and sour-cream 

 butter, respectively. According to the calculations made, a little over 

 60 per cent of the albuminoids contained in butter belong to this "serum 

 difference'' or the membranes of the fat globules. The author explains 

 the presence of the minute serum particles in the butter by a general 

 breaking up of the membranes during the churning, particles of these 

 being distributed in the butter in immense numbers. The serum drops, 

 of which there are about 3 to 4 millions per cubic millimeter of butter 

 in faultless goods ("clear" butter) and toward 13 millions in so-called 

 "thick'" butter, were shown to bear a definite relation to the brine- 

 leaking tendency of certain kinds of butter, and to certain butter faults. 

 Butter losing brine on standing always contained comparatively few 

 drops and of a larger size than butter that did not lose brine on stand- 

 ing. The water content of the butter did not necessarily determine 

 whether or not brine would separate from the butter on standing; 

 some of the butter with the highest water content in the Permanent 

 Danish Butter Exhibitions did not lose brine, and vice versa. 1 



Specific gravity of butter and serum components. — The following aver- 

 age data were obtained for the specific gravity of butter and the com- 

 ponents of the serum (except where otherwise stated the data refer to 

 15° C, water at 15° C. beiug=l): 



Specific (/rarity at 15 C. 



Salted butter ( 14 determinations ) 0. 9625 



Fresh nnsalted butter: 



"Thick" butter (water 14.80 percent) 10 determinations 9480 



"Clear " butter (water 13.74 per cent) 9 determinations 9466 



Sweet-cream butter (water 13.08 per cent ) li determinations 9458 



Butter fat (6 simples ) 9341 



(Fleischmann 0.9303) 



I Blyth 0275) 



Butter fat at 100 C. (water at 15 =1) 5 samples 8682 



Butter fat at 100 C, 53 samples 8667 



(Konig 0. 8650-0. &680) 



I Pfeiffer .8675) 



( Skel weit . 8672) 



Milk sugar (water free) 1. "'673 



(Equivalent to 1.524 for C^H^On +H2O (Schroeder 1.525. water 

 at 4° C=l . ) 



( lasein (4 determinations) 1. 3424 



(Assuming the specific gravity of the ash equals that of milk 

 ash. 3.13, see below. ) 



Casein, ash -tit e 1. 3379 



Membrane albuminoid of fat globules (3 determinations) 1.3675 



Membrane albuminoid of fat globules, ash-free 1. 3115 



Milk ash (2 determinations. 17-J C. ) 3. 1305 



Butter serum in "thick" butter 1. 0310 



Butter serum in ■• clear" butter 1.0290 



— F. W. WOLL. 



'Rpts. Copenhagen Experiment Station, 28, 1893 (E. S. R, 5, p. 722); 33, 1895 

 (E. S. R., 7. p. 627). 





