LACTIC ACIO. 259 



remarked, that when an excefs of acid is ufed, it is found to 



exift in the ferum ; whereas, when the necefiary quantity is 



ufed, it is found in the cheefe only. 



After having feparated the cheefy matter the ferum was It is the fame 



clarified : the wheys were found (o have all the fame tafie and <! uid in th f dif * 



7 . ierent cafes. 



colour, and pofTefled the fame degree of acidity. 



This frefh whey turns fyrup of vioiets green : This property It affects fyrup 

 maft be attributed only to the union of the yellow and blue, of vlolets * 

 and not to faline matters, as chemifis have afferted. Whey, 

 which has loft its colour by expofure to the air, reddens the 

 fyrup of violets. 



The means employed to afcertain the acids which had been 

 ufed to coagulate the milk, did not exhibit even the fmalleft 

 quantity when the operation was performed with exaclnefs. 



I made a comparative examination of the ferum which had Sour ferum by 

 become four in the open air ; and I obtained", by expofing the ex P° furc of 

 milk, the fame phenomena as were pointed out in the fecond 

 fection and third experiment. 



The fpontaneous ferum differed, 1. In its tafie, which was differed from 

 more acid; and, 2. Its colour, which is dull and whitifh, other ferum * 

 owing to white filaments which are feparated. It may be 

 had clear by filtration, without acquiring the colour of frefh 

 whey. 



The cheefy matter refulting from the feveral experiments Cheefy matteri 

 before related, gave the fame red with tincture of turnfole. 

 If it be calcined and treated with the known re-agents, the 

 prefence of fulphuric acid will be indicated if this- acid has 

 been employed in the coagulation, and alumine when alum 

 has been made ufe of. 



I do not therefore fee any inconvenience, in preparing whey Alum or fulphu- 

 for the purpofes of pharmacy, to coagulate the milk with one rlc acid ™ ay be 

 or the other of thefe fubftances, more efpecially if the precau- coagulate milk. 

 lions I have mentioned be attended to. Thofe who have 

 thought it unwholefome to coagulate milk with alum, have 

 doubtlefs made no experiment on the fubjecl. 



Oxigen gas is not abforbed by the ferum ; even agitation Oxigen and fe- 

 does not facilitate its union. rum< 



The a&ion of lime-water, the folution of barytes, ftrontian, Other agents. 

 and fome metallic falts, though already known by chemifis, 

 require to be again examined, and will enable me to explain 

 the procefies for obtaining laclic acid, 



$ 2 SECTION 



