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LXXIV. Intelligence and Miscellaneous Articles. 



ANALYSIS OF CASEUM. 



MVOGEL employed the method adopted by Berzelius for the 

 • preparation of this substance, which consists in isolating 

 from milk by dilute acids. 



As the great quantity of fatty substances contained in milk occa- 

 sions many difficulties in the washing and purification of caseum, 

 M. Vogel made use of buttermilk, which is more completely de- 

 prived of the greater part of the butter than mere skimmed milk. 



The buttermilk was treated with dilute sulphuric acid ; with this 

 the caseum combined, and was afterwards precipitated from it in the 

 state of a white magma : the serum was separated by straining ; the 

 compound of sulphuric acid and caseum was agitated and digested 

 with distilled water, and then washed on a filter. This manipula- 

 tion was repeated, until the washings evaporated on platina foil left 

 no residue. 



After the washing, the compound was diffused in distilled water, 

 agitated, and digested with carbonate of barytes, in order to combine 

 the barytes with the sulphuric acid, and dissolve the caseum in 

 water. The liquor was filtered, and the aqueous solution evaporated 

 to dryness in a water-bath. The residue of the evaporation was a 

 yellowish white mass, transparent, and resembled gum arable in its 

 property of giving a mucilaginous liquid with a small quantity of 

 water. The dry mass was pulverised, digested with cether, to re- 

 move the last traces of fatty matter, and then dried at 212". 



A small quantity was calcined in a porcelain capsule, and the 

 complete incineration was aided by the addition of concentrated 

 nitric acid drop by drop ; the ashes amounted to the enormous quan- 

 tity of 21 '454 per cent. ; these ashes consisted of phosphate and car- 

 bonate of lime, and some carbonate of barytes, which had been acci- 

 dentally introduced. 



Omitting the ashes, two analyses gave 



100- 100- 



M. Vogel remarks that albumen, fibrin, and caseum possess se- 

 veral properties which are very nearly allied ; all three may exist 

 in two states, dissolved and coagulated, with this difference, that 

 fibrin coagulates of itself as it issues from bodies, that caseum is 

 coagulated in a manner not hitherto understood by pressure, and 

 that the coagulation of albumen is es])ecially produced by heat. All 

 three also possess the property, in the state of coagulum, of dissolv- 

 ing when heated in an excess of concentrated hydrochloric acid, 

 and yielding a fine lilac-coloured solution, a property which may be 



