116 HAEMIN. [BOOK i. 



prismatic crystals 1 . Such crystals can be obtained from any blood 

 stain, as on cloth or linen, by cutting out the stained tissue and 

 heating it with glacial acetic acid, taking care to add a small crystal 

 of sodium chloride. The evaporated residue contains the crystals. 



Properties These crystals are of a dark brown and sometimes 



of-naemin. O f near ly a black colour, and present the form of 

 rhombic plates sometimes arranged in radiating bundles. 



Haemin is insoluble in water, alcohol, ether, chloroform, and in 

 cold dilute acetic and hydrochloric acids. It is however soluble in 

 caustic alkalies, in alcoholic solution of potassium carbonate, and in 

 boiling acetic and hydrochloric acids. It dissolves in concentrated 

 sulphuric acid, forming a violet-red liquid, which evolves hydrochloric 

 acid when heated. 



Hoppe-Seyler has prepared this body by a method to be afterwards 

 referred to, and he considers it to be hydrochlorate of haematin and 

 ascribes to it the formula CggH^NgFe/^SHCl;, he found the com* 

 pound to contain 5'18 per cent, of chlorine. 



It is held by Thudichum that haemin contains no chlorine, and 

 he therefore looks upon it as crystallized haematin. Hoppe-Seyler 

 however asserts that he has never obtained haemin crystals which 

 were free from chlorine, and the statement agrees with the original 

 observations of Teichmann who held the presence of chlorine to be 

 indispensable to their formation. 



Prepara- Whilst it is very easy to prepare in a few minutes 



tion of hae- microscopic crystals of haemin, the difficulties attending 

 min in large the preparation of considerable quantities in a pure con- 

 dition are considerable ; the following method has been 

 followed by Hoppe-Seyler: 



Defibrinated blood is mixed with a large excess of a solution of 

 sodium chloride, containing ^th its volume of saturated solution of 

 NaCl, and set aside in a cool place so as to allow the corpuscles to 

 subside; the clear supernatant fluid is decanted and the magma of 

 corpuscles is mixed with some water, placed in a flask, and shaken up 

 with ether ; the ethereal solution is decanted, the solution of colouring 

 matter is filtered and evaporated to dryness in shallow basins. The 

 residue can be readily pulverized. The powder is passed through a 

 sieve and then weighed. It is then mixed with glacial acetic acid in 

 a mortar, the mass is washed into a basin by the aid of more glacial 

 acetic acid, which is then added in such quantities that two litres of 

 glacial acetic acid are employed altogether for every 100 grammes of 

 the powder. The mixture, which has been mixed as well as possible, 

 is then heated on the water bath, the temperature of which is allowed 

 gradually to rise; the process of stirring is carried on from time to 

 time and the mixture is allowed to remain for some hours at 100C. 

 Crystals soon commence to form, though long heating is required 



1 Teichmann, Zeitschrift f. rat. Medizin f. Henle und Pfeuffer, 1853, Vol. m. 

 p. 375 and Vol. vm. p. 141. 



