IACTIC ACID. 



143 



and fecondly, becaufe whey formed by the ufual procefs, is 

 more or lels acid. 



Experiment 1. Recent milk gives a red colour to the paper Exp. t. Milk 

 and the tinclure of turnfole. reddens turnfole. 



Experiment 2. It milk be difiilled in clofe veffels, and the?*?* 2 \, I ! :af ~ 



. . rords acid by dif- 



product Separately taken, the firft is not acid; the fecond tillation, and 



reddens turnfole, and flightly precipitates the nitrate offilver ; continues acid. 



and the third has no ad ion on the tinclure. At this period, 



the milk is not yet decompofed, but ftill reddens turnfole. It 



appears that the remaining acid is no longer volatile, but is 



retained either by the animal matter, or by (ome other fub- 



Itance. 



Experiment 3. If milk be coagulated with a mineral or ve- Exp. 3. Whey 

 getable acid, the whey is feparated, without retaining a par-j^™^ C °* s ^-~ d 



tide of the acid made ufe of. retains none of ' 



I muft however obferve, that fome deception would fol- the acid uldt ' 

 low, if the ferum only were examined, which is obtained by 

 the fulphuric acid, or by allum, becaufe the precipitate afforded 

 by barytes, is not entirely re-diffolved by the nitric acid. I 

 am fatisfied that this arifes only from a (mall quantity of ful- 

 phurale of potafh contained in the ferum, as is evidently 

 proved, when the whey is feparated by any other fubftance 

 not of an acid nature. 



It is not true therefore as many chemifts have advanced, that Exp. 4. whey 

 the acid feparates the cafeous matter, by uniting with the ferum. t^To^d? "" 



Experiment 4. If milk be expofed to the air at the tempe- competed, iaaifc 

 rature between 12 and 20 degrees (about 66 Q Fahrenheit) the. acid * 

 feparation takes place in twenty-four hours. The curd has 

 a more acid flavour than that of experiment 3. Hot water 

 caufes it to lofe its four tafte, and acquires the property of 

 reddening turnfole. 



We here find nearly the fame properties in the cheefy mat- 

 ter, when fpontaneoufly formed, and when feparated by acids. 



Experiments. The fame experiment being made with the Exp. 5. Milk 

 pneumatic apparatus, was attended with no abforption of air, ^ ne o y fl> ' 

 or difengagement of elafiic fluid. The only difference was, neither abforbs 

 that the feparation of the cheefy matter did not take place f or nor S ivesouCair ' 

 feveral days. Part floated on the liquid, and the other occu- 

 pied the bottom of the veffel. 



Experiment 6. A bottle was filled with frefh milk, and well Exp. 6. Milk 

 corked. Some days afterwards, the cheefy matter had fepe- J ec ™K ed '■ 



J ' J * Ipont. jn a doled, 



fated. As foon as the feparation was complete, the cork was bottle, gives co- 

 ntended to be extracted, but it flew out with violence and bonic ac;d ' 



noife, 



