492 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



The red blood corpuscles, after separating the serum and washing with -9 

 per cent, sodium chloride solution, are mixed with twice their volume of water 

 and warmed to 37. Ammonia is added to dissolve the stroma of the cor- 

 puscles and the solution is exactly neutralised with dilute hydrochloric acid. 

 A quarter of its volume of alcohol is added and the mixture is kept at o. 

 Crystals separate out on standing. They are separated, washed with alcohol 

 and water in the above proportions and recrystallised by solution in two 

 volumes of water, adding a quarter volume of alcohol and cooling to o. 



Properties. 



The crystals of oxyhaemoglobin obtained from the blood of different 

 animals are generally microscopic, seldom exceeding 5 mm. in length and of 

 a yellow-red colour. They vary in shape. Figs. 62-65 show some of the 



FIG 62. Human. 



(After Funke.) 



forms of crystalline oxyhaemoglobin. Those from guinea-pig's and rat's 

 blood are generally tetrahedra or octahedra, those from squirrel's blood are 

 six-sided plates, those from goose's blood are rhombic plates, those from dog's 

 and horse's blood are usually four-sided prisms. 



Fio. 64. Squirrel. Fio. 65.-Guinea.pIg. 



(After Funke.) 



They generally contain water of crystallisation an amount of 14-35 per 



nt. has been evolved on heating crystals dried in vacua to 116 The 



crystals if carefully dried at low temperatures can be heated to 100 without 



decomposition, but decomposition occurs if they are moist, as shown by the 



