300 COLOURING MATTERS. 



phuric or hydrochloric acid has been added, forming a brown 

 solution, which, on saturation with an alkali, assumes a blood-red 

 colour. Water, acidulated with the same acids, exerts no solvent 

 power on hsematin, and consequently a precipitation is induced by 

 the addition of water to alcoholic solutions of this substance. Con- 

 centrated sulphuric and hydrochloric acids do not dissolve heematin, 

 but they abstract a little of the iron. After trituration with sul- 

 phate of soda, it dissolves for the most part in w r ater. Even very 

 dilute solutions of the caustic alkalies or their carbonates in water 

 or alcohol dissolve hsematin in almost every proportion. A potash- 

 solution, boiled and then saturated with an acid, yields a form of 

 heematin which is no longer soluble in a mixture of alcohol and 

 ammonia. The potash-solution, on boiling, assumes first a dark 

 red, and subsequently a green tint. The ammoniacal solution 

 gives off its ammonia during evaporation ; moreover, heematin does 

 not absorb ammoniacal gas. The colour of the ammonia- solution 

 of hsematin is not affected by carbonic acid, oxygen, or nitric oxide ; 

 sulphurous acid gives it a bright red tint, and sulphuretted hydrogen 

 makes it slightly darker. 



Haematin is completely precipitated from its ammonia-solution 

 by the salts of oxide of silver, of lead, and of copper ; if the solu- 

 tion of hsematin in alcohol, acidulated with sulphuric acid, be 

 boiled with oxide of lead, it becomes entirely decolorised. 



When heated in an enclosed space, hsematin puffs up, and, 

 without melting, yields empyreumatic ammoniacal vapours and a 

 reddish brown oil, and leaves a rather small porous charcoal, which 

 on combustion yields a red ash. Phosphorus and sulphate of prot- 

 oxide of iron may be boiled with heematin without in any way 

 affecting it. 



Treated with concentrated nitric acid in the cold, it dissolves 

 into a brown fluid, and developes nitrous acid ; when boiled with 

 this acid it is entirely destroyed. 



If chlorine be allowed to act on hsematin mixed with water, all 

 the iron of the hsematin dissolves as perchloride of iron, and there 

 is a deposition of white flocculi, which are soluble in alcohol and 

 ether but not in water, develope a little chlorous acid when dried 

 (at 100), and then form a light straw-coloured powder. This 

 powder is unaffected by hydrochloric acid, but dissolves in 

 alkalies, forming a reddish solution ; according to Mulder, it consists 

 of chlorous acid arid hsematin freed from its iron. If chlorine gas 

 be passed over dry hsematin, they unite and form a dark green 

 compound which is soluble in alcohol, exerts no action on vegetable 



