CREAM RAISED BY GRAVITY PROCESSES. 177 



slowly in the pans, and the final temperature (55-59 F.), 

 while not very favorable to the bacteria, is yet by no means 

 unfavorable; and as the milk is under the influence of this 

 and still higher temperature for at least thirty-six hours, 

 it is evident that a considerable bacterial growth will take 

 place. It is also often very difficult in this method to 

 fight especially the lactic-acid bacteria, and older writers 

 on dairy matters, as Martens, dwell at length on the diffi- 

 culty of keeping the milk and the cream sweet when this 

 method is followed. The difficulty of keeping the wooden 

 pans clean is another objection to the method. Martens 

 also maintains as the first duty of the dairywoman " to 

 have especial attention directed toward the cleaning of 

 the dairy utensils. She should always be present at the 

 cleaning of the milk-pans and personally examine every 

 pan." 



In spite of these disadvantages, the method when 

 properly conducted gives excellent, well-keeping butter. 

 The explanation doubtless is found in the minute cleanli- 

 ness and dryness (see p. 112) which must be observed where 

 it is used. 



In the Gussander method, invented in the '40's by 

 Major Gussander in Sweden, the milk is strained in still 

 thinner layers than in the preceding method, and the tem- 

 perature is generally higher. The rising of the cream is 

 facilitated by the short distance to the surface and by the 

 lower viscosity of the medium through which it has to pass. 

 The milk is here not kept in cellars, as in the Holstein 

 method, where a certain moisture of the atmosphere is 

 likely to be retained, but in light, cheerful rooms, where 

 scrupulous cleanliness is observed, and where fresh, dry air 

 can all the time be maintained. Cleanliness was also fa- 



