HEATING MILK FOR BUTTER. 45 



mass, next to the vessel, that it will curdle the milk outside, 

 unless it is stirred repeatedly and very carefully ? 



Mr. Arnold. It avouIcI injure the butter materially. You 

 cannot heat milk after it is sour without doing injury to the 

 butter. As long as it is sweet, you can heat it up to the boil- 

 ing point, as long as it will not respond to the acid test. It 

 will soften the caseine a little and the butter, but the butter 

 will be very nice and keep well, if heated to the boiling point, 

 an}' time when it is sweet. But if you heat when it is sour, 

 when it will respond to the acid test, you invariably injure it. 

 Scalded cream churns more easily than cream that is not heated. 



Question. How much saltpetre would you use to a gallon 

 of cream? 



Mr. Arnold. I would use sixteen times as much salt as 

 saltpetre, and put in enough salt to make the cream taste a 

 little salt. I would not put in a great deal. 



Mr. Ellsworth. About two tablespoonfuls to a gallon of 

 cream ? 



Mr. Arnold. I would put in a little more than that. It 

 would not hurt it, at any rate. I would put in enough salt to 

 make it taste fairly brackish. That is sufficient to check the 

 changes. 



Question. Would you use saltpetre in cheese-making ? 



Mr. Arnold. I never have used but very little of it. 

 There was no bad effect from it, and no decided effect, any 

 way. I have heard some cheese-makers say they produced a 

 better effect when they used saltpetre than when they did not 

 use it, especially in making skim-milk cheese ; that the curd 

 was very tender. 



Question. What is the best way to preserve rennet? 



Mr. Arnold. By drying and exposing to the air, so that 

 all the odor possible may work out of it. 



Question. How is it to be cured and kept? 



Mr. Arnold. For practical purposes, it is generally best 

 to dry it. Blow it up, as you would a bladder, tie the ends, 

 and salt the ends where it is tied to keep them from tainting. 

 Do not salt the rest. The changes which occur in it, which 

 develop rennet, are put back by salt. That is the best way. 

 The next best way is to salt it very lightly, and stretch on a 

 crotched stick or a bow, so that it will dry readily. The 



