3l& *N MILK AND BUTT1R. 



XV. 



Abftracl of a Memoir on Milk. By M* Then ard.* 



T » 



f mT ntpart * rnenioir wh5cn * rca( * to tne Philoroalic Society in 



Praircal laft, I mewed that milk always contains the iieti 

 acetous acid in a greater or lefs quantity. At the fame period 

 Meflfrs. Fourcroy and Vauquelin found that it alio contains 

 phofphate of magnefia, and that the lactic acid of Scheele, or 

 that which is obtained from ferum of milk fpontaneoufly coa- 

 gulated, is merely the acid of vinegar combined with an ani~ 

 mal matter., So that in t{ie prefent (late of our knowledge 

 we muft confider milk as coropofed of, 1. Water y 2. Acetous 

 acid; 3. Cafeous matter; 4. Butteraceoijs matter; 5. Sugar 

 of Milk; 6. Extractive matter; 7. Muriate of fad a and of 

 potalh; 8. Sulphate of potath ; 9, Phofphate of lime; 1Q. 

 Phofphate of magnefia. 



Of thefe eleven fubftances there is one whjch I particularly 



examined feme months ago, namely cream. I was defiroivs 



of ascertaining the circumftances which govern its feparation, 



and particularly its transformation into butter. 



The reparation J had before obferved that milk coagulates as readily in 



butter does'not p'°W as m °P en ve ^^ s J I know that no gas is difengaged in 



require actefs of this decompotition, and that, in order to effect it with ra- 



**• pidity, it is needful only to raife the temperature to between 



20° and 40° (Reaumur I fuppofe; and, if fo, anfwering to 



77° and 122 p Fahrenheit). It was clear, therefore, that the 



air contributes neither to the formation nor the feparation of 



cream, but that it exifts ready formed in milk; but it remained 



to be fliewn what are the principles which enter into its com r 



pofition. Being perfuaded, from various obfervations I had 



made, that it is only an intimate mixture of butter, cheefe, 



and ferum, I proceeded to ascertain this point by mixing a 



pint bottle (Englith quart) of recent cream nearly to its neck, 



from which I difplaced the remaining air by carbonic acid. 



I then clofed it well, and agitated it ilrongly in eyery direction 



for half an hour; at the end of which time the contents having 



loaoia 



♦ Soc. Philomath, No. 06, 



become 



