BY DR. BURDON-SANDERSON. 197 



called hydro-chlorate of haematin. Its carbon, nitrogen, and 

 iron are in the same relative proportions as in haMnatin, but 

 necessarily it contains a little less iron per cent, than that 

 body. 



The mode of preparing the so-called Teichmann's crystals 

 in other words, the mode of obtaining ha3min for the purpose 

 of demonstrating its crystalline form microscopically has 

 been fully described in the histological part (Chap. I., p. 34). 

 Ilnemin may be obtained from blood in quantity, as follows, 

 but the process is one which appears to present great difficulty, 

 as it frequently fails. Defibrinated blood is diluted with a vol- 

 ume and a half of distilled water. The transparent liquid is 

 then precipitated with neutral acetate of lead, for the purpose 

 of separating the albumin. The excess of lead (with respect 

 to which it is desirable to be careful not to add more than is 

 necessary) having been got rid of by the addition of a con- 

 centrated solution of carbonate of soda, the liquid is filtered, 

 and the filtrate evaporated to dryness either in the air or in 

 vacuo. The dry residue is then finely powdered and rubbed 

 up with fifteen times its own weight of glacial acetic acid, to 

 which a trace of chloride of sodium has been added. The 

 brown liquid thus obtained is introduced into a flask and 

 warmed in the water bath until it is entirely dissolved, and the 

 solution is mixed with five times as much distilled water, and 

 allowed to stand for many days, protected from evaporation. 

 The crystals collect on the bottom of the beaker and may be 

 readily purified by repeatedly treating them with distilled 

 water, allowing them to subside and then decanting. As hoa- 

 min contains chlorin, it cannot be prepared from hrcmatin 

 unless chlorides be present. When it is prepared from blood, 

 the quantity of chloride of sodium present is sufficient, so that 

 the addition of that salt is not essential. The solution of ha-- 

 iiiin in hydrochloric acid gives no characteristic spectrum. 



21. Haematin. Haematin can only be obtained in a state 

 of perfect purity from the crystals of haemin, the mode of pre- 

 paration of which has just been given. The process is simple : 

 the hrcmin crystals are dissolved, i. e., decomposed in ammonia. 

 The solution of luumatin thus obtained is evaporated to dry- 

 ness, the residue is then extracted with water, which removes 

 the chloride of ammonium, and dried. The product is pure 

 luiMnatin. It is insoluble in water, alcohol, and ether, soluble 

 in alkalies and alkaline carbonates, but not soluble in acids 

 without decomposition. 



In the impure state, haematin may be obtained in various 

 ways. The change occurs more gradually at ordinary tem- 

 peratures in solutions of blood, or hemoglobin, which are de- 

 cidi-dly alkaline, whether the alkalinity is di-rivcd from potash, 

 soda, ammonia, or their carbonates. Solutions of haemoglobin 



