m 



144 THE GENESEE FARAIEE. ^ ^' 



and it* is to the presence of these three acids, in a greater or less proportion, that the 

 rancidity of butter is owing. The cause, therefore, of butter becoming rancid, is the 

 presence of the nitrogenous compound, casein. The prevention is attained only by con- 

 siderable trouble and care. 



Saturated solutions of saline and other substances are found to arrest this tendency to 

 decomposition. Among them is common salt, which is most generally used for this 

 purpose. It should be as free from all impurities as possible, especially the salts of lime 

 and magnesia, which are found to give the butter a bitter and otherwise disagreeable 

 flavor. These salts, being soluble in less water than common salt, may be got rid of by 

 pouring about a quart of hot water on eight or ten pounds of salt, stirring it well for a 

 short time, and then straining it through a fine cloth. The impurities will go off in the 

 liquor, -which may be given to stock, &c., and the salt in the bag can be dried and kept 

 for butter-making purposes. 



When the butter is taken from the chum, it is usual either to wash it till it imparts 

 no color to the water, or to press out the buttermilk by kneading and pressing, using no 

 water at all. Both methods have their advocates, and both have certain advantages 

 over the other. The washing doubtless removes most of the casein and sugar of milk, 

 and is, we think, decidedly the best practice. All the water that is left in the butter, be 

 it more or less, must be saturated with salt ; that is, must have dissolved as much as it 

 is capable of taking up : so that it is necessary to free the butter from all the water 

 possible, or else it will be too salt. We insist particularly on this point, because it is 

 proved by experience that butter, however good it may be when packed, will not keep 

 if there is any water, or buttermilk, or curd, that is not well saturated with salt. It is 

 also necessary to exclude the atmosphere as much as possible from the butter, its oxygen 

 greatly facilitating decomposition. 



Of the great necessity of cleanliness in every operation connected with the dairy, it is 

 unnecessary to remark, further than that cream is remarkable for the rapidity with which 

 it absorbs different gases ; so that great care should be taken to keep the dairy clean, 

 and close all apertures through which any offensive gases might enter. 



The chemical changes that take place in the manufacture of cheese, are very similar 

 in their nature to those just described in our remarks on butter-making, and can easily 

 be understood. 



When milk is fii-st drawn from the cow, it is always alkaline, in consequence of the 

 soda contained in it. If to a portion of this milk vinegar or any other acid be added, 

 the milk is immediately curdled. When in this state, if a little soda or potash is added, 

 sufficient to make the mixture slightly alkaline, the curd disappears, and the milk is 

 restored to its original state. The reason for these changes is, that curd is insoluble in 

 pure water, or in water containing an acid ; but is soluble in water containing an alkali 

 — soda, potash, or ammonia. Now, milk contains soda, which imites with the curd, 

 rendering it soluble ; but Avhen an acid is applied, it unites with this soda, neutralizing 

 its alkaline properties, and the curd is left in an insoluble condition, or is precipitated. 

 When milk is kept for any length of time at a temperature favorable for fermentation, 

 a cheijiical chd,nge takes place — the sugar of milk, imder the influence of the casein, is 

 transfornaed into lactic acid, which unites with the soda, taking it away from the curd, 

 and thus leaving it in an insoluble state, or precipitates it in the same manner as though 

 vinegar or some acid had been added. 



The various processes of cheese-making are only diSerent modes of hastening this 

 decomposition of the sugar into lactic acid, and arresting it at the proper time. The one 

 generally adopted in this country — using the prepared stomach of the calf or hog — is 

 doubtless the best method at present known. Of the action of rennet, there is much 

 ignorance, and consequently much diversity of opinion. From the fact that gastric juice 

 will immediately curdle milk, it was very reasonable to suppose that the action of rennet 



