118 THE BLOOD. 



sodium hydrate, then add enough to dissolve the precipi- 

 tate, warming if necessary. Alkali hsematin is formed. 

 Examine the spectrum. 



252. Acidify slightly a solution of blood, and heat to 

 boiling. Notice the coagulated albuminous substance and 

 the dark-colored haematin coming from the decomposition 

 of the oxyhaemoglobin. 



253. Filter out the hasmatin or use instead a drop 

 of fresh blood and prepare haemin crystals from it by first 

 drying thoroughly on a glass slide, then adding a minute 

 amount of sodium chlorid. Cover with a cover glass ; add 

 a drop of glacial acetic acid, which will flow under the 

 cover. Then heat over a small flame until the acid boils. 

 After cooling examine under a microscope. The crystals 

 sometimes are better if the acid is added and the slide 

 heated two or three times. 



254. To prepare a large amount of hsemin, precipitate the 

 corpuscles from, defibrinated blood by the addition of a large excess 

 of a salt solution which contains 1 volume of a saturated salt 

 solution in 10 to 20 volumes of water. After twenty-four hours 

 pour off the solution and rinse the precipitated corpuscles into a 

 flask by the aid of a small amount of water. Add half its volume 

 of ether, shake, and after pouring off the ether which removes 

 most of the fats allow the solution of blood-coloring matters to 

 evaporate in flat dishes at ordinary temperature to a syrup. Mix 

 this with 10 to 20 volumes of glacial acetic acid and heat in a 

 flask one or two hours on the water-bath. Then pour into a 

 beaker, add several volumes of water, and allow to stand several 

 days. Wash with water and remove the albuminous substances 

 by boiling with acetic acid. 



255. Saturate 2 or 3 cubic centimeters of blood with 

 carbonic oxid by passing illuminating gas through it. Add 

 to it twice its volume of sodium hydrate solution, specific 

 gravity, 1.3, containing about 27 per cent. ISTaOH. Do 



