326 EXTRACT OF MEAT. CREATINE. [BOOK I. 



When the solution is boiled, the haemoglobin and the soluble 

 proteids which it contains are coagulated and, on filtering, a clear 

 liquid is obtained containing the salts of muscle, certain non-nitro- 

 genous organic bodies, such as glycogen, inosit, lactic acid, &c., and 

 a mixture of nitrogenous organic bodies, mostly basic in their cha- 

 racter; these are creatine, creatinine, carnine, xanthine, hypoxan- 

 thine, and perhaps urea. To the residue obtained by evaporating an 

 aqueous infusion of muscle, the name of extract of meat is given ; 

 several extracts of meat exist in commerce, which are substantially 

 obtained in the way we have mentioned and which may be employed 

 in the laboratory for the preparation of the various nitrogenous 

 organic bodies to be now described. Beef-tea is an aqueous extract 

 of meat, and contains the same substances as are present in the 

 solid extract of meat. 



Creatine. C 4 H 9 N 3 2 + H 2 0. 



This body occurs in only two of the elementary 

 tissues of the body, viz. in muscular and nervous tissue. 

 It has never been found in any glandular organ. In 



small quantities it occurs in the blood, but it is present in muscle in 



largest amount. 



I. (Liebig's method 1 ). Muscle is reduced to a fine state of division, 

 as for example by the use of a sausage machine, and then mixed with 

 one half its weight, or its own weight, of cold water, and set aside for 

 some hours. The insoluble matter is separated on a linen filter 

 from the liquid, and the former is subjected to strong pressure. It is 

 then treated with a quantity of water equal to that first used, and, 

 after some hours, the process of filtration and pressing repeated 

 as before ; the water used for the second extraction may be employed 

 afterwards to extract a fresh quantity of meat. The liquid thus 

 obtained is then boiled, by which means the albumin which it 

 contains is coagulated ; after removing the albumin by filtration, 

 baryta water is added to the filtrate, so as to precipitate the whole of 

 the phosphates present. The excess of baryta present in the solution 

 is removed by passing through it a current of C0 2 , and, after filtering, 

 the filtrate is concentrated by evaporation on the water-bath, until 

 it has a syrupy consistence ; it is then set aside for some days. 

 Creatine separates out in the form of crystalline crusts adhering to the 

 bottom of the vessel; the mother liquor is poured off and the 

 crystals washed with cold alcohol; these are then dissolved in 

 boiling water, and the solution decolorized by means of animal 

 charcoal. On evaporation, crystals of creatine separate which are 

 purified by recrystallization. 



II. (Neubauer's method 2 ). The watery extract of muscle is preci- 

 pitated by solution of lead acetate, the solution is treated with 

 sulphuretted hydrogen to remove the excess of lead, and is cautiously 



1 Liebig, Ann. d. Chem. u. Pharm. Vol. 62, p. 257. 



2 Neubauer, Ann. d. Chem. u. Pharm. Vol. 119, p. 27. 



