[ 758 ] 



days. The proportion of alcohol generated is i to 2 per 

 cent. 



1,311. Butter. Though some of the caseous bacilli are 

 classed as butyric, it is not to be supposed, that butter is a 

 product of fermentation. Butter can be made from fresh 

 milk as well as from sour i. e., fermented milk. Butter made 

 from sour milk or sour cream, keeps better, and by souring 

 a larger proportion of butter is obtained. Butyric acid, 

 no doubt, is obtained as a residue from the breaking down 

 of milk-sugar which is effected by various lactic ferments 

 (C 6 Hi 2 O 6 = C 4 H 8 O 2 + 2CO 2 +H 4 ). The presence of butyric 

 acid can be detected in all ripened cheeses. As the fat 

 globules of milk come together more readily if their caseous 

 envelopes are decomposed by fermentation, caseous fermen- 

 tation also plays a part in most of the ordinary processes 

 of manufacture of butter. If butter is made from cream, 

 milk should be used in as fresh a state as possible, and if 

 no centrifugal separator is employed the milk should be set 

 in shallow pans, fermentation being prevented by render- 

 ing the milk as cold as possible by rapidly passing the fresh 

 milk through a refrigerator, that the milk may be set at a 

 temperature of 12 to 15 C (say, 55F). If fermentation sets 

 in, coagulation takes place which offers resistance to fat 

 globules rising readily to the surface. After the fat globules 

 have come to the surface, the top portion of the milk is 

 skimmed off. This, containing all the fat globules is called 

 the cream, and from this butter should be made after fermen- 

 tation, or fresh milk can be fermented and butter made from 

 the fermented sour milk or dahi. In this climate it is difficult 

 to secure the proper temperature for setting of cream, and it 

 is better therefore to obtain butter from dahi or from clotted 

 cream (shar] as is the general practice of the country. The 

 latter method is practised in Devonshire also where the milk is 

 set in deep tinned vessels, or pans of iron or of brass, and after 

 12 hours' standing without disturbing them, fire is lit and 



