EXAMINATION OF MUSCULAR TISSUE. 21 



through muslin and press out the residue completely in a 

 press. 



Heat the combined extracts to boiling in a thin-walled 

 tinned vessel, stirring constantly, in order to precipitate the 

 albumin. The fluid surrounding the coagulum of albumin 

 must be quite clear. If it is not clear add a few drops of 

 acetic acid. Filter from the albumin, which is colored some- 

 what red from the blood-pigment mixed with it, and let cool 

 completely. The extract, entirely free from albumin, is 

 cautiously treated with basic lead acetate solution as long as 

 a precipitate forms, then filtered, the filtrate freed from lead 1 

 by means of hydrogen sulphide and again filtered. Test a 

 portion of the filtrate to see if it is free from lead. When 

 hydrogen sulphide is passed through it, no blackening should 

 occur ; if it does, then the filtrate must be again treated with 

 hydrogen sulphide. The filtrate is now evaporated, on the 

 water-bath, to the consistency of a thin sirup, and this is 

 allowed to stand for some days in a cool place. The creatine 

 crystallizes out. It is separated from the mother-liquor by 

 filtering, if it separates in large crystals, or, if it crystallizes 

 in small crystals, by pouring the whole mass on a porous 

 plate. It is then recrystallized from a little hot water. 



Creatine, C 4 H 9 N 3 2 +H 2 0, forms transparent, colorless,, 

 hard, rhombic prisms, which easily lose their water of crys- 

 tallization. It dissolves in 74 parts of cold water, more- 

 readily in hot, very slightly in alcohol, and not at all in ether. 

 The solutions react neutral. Creatine has no characteristic 

 reactions. For its recognition we make use of either its con- 

 duct when heated cautiously or its conversion into creatinine. 



1. A small portion of the creatine is cautiously heated 



1 Instead of this we may also, in order to save time, precipitate the 

 greater part of the lead by the cautious addition of sulphuric acid and 

 then separate the remainder by means of hydrogen sulphide; however,, 

 the lead sulphate passes readily through the filter. 



