178 CIRCULATING FLUIDS: 



We may safely calculate tliat the whole of the free fat has heen 

 taken up, after six or seven extractions with ether. If, after- 

 wards, the ha3matin should still be found to contain fat, some 

 of the fatty acids must have been present, and acted upon by 

 the acidified alcoliol. 



Albumen. Errors may arise in the determination of the 

 albumen. These may be due, in the first place, to want of 

 care in drying and pulverizing the blood. If the powdered 

 blood has been allowed to dry into a cracked, brittle, tough, 

 hard mass, which can only be repulverized with difficulty, and 

 usually with considerable loss, then, only a portion of the 

 hsematoglobulin is taken up by the spirit, some of it now ap- 

 pearing of a yellow or gi ay-green colour, while another part of 

 it occurs in the form of coarse black fragments, resisting the 

 action of alcohol. This albumen has a somewhat red tint, and 

 upon incineration leaves an ash, which is tolerably rich in iron. 



Another source of error may lie in the spirit, which may be 

 either too strong or too weak. I have always found a mixture 

 of equal parts of alcohol of 85 — 90^, and of water, succeed 

 best. I have occasionally found that with all precautions, and 

 after boiling the residue with spirit until no more hsemato- 

 globulin was taken up, the albumen has still retained its red 

 tint, and left an ash abounding in iron. I have never been able 

 to ascertain the reason why diluted boiling alcohol should occa- 

 sionally fail in the perfect extraction of the h?ematoglobulin. 



If, after continuous boiling with dilute alcohol, the albumen 

 still retains a red tint, I heat it with alcohol of "80 — •82, in 

 the same flask, and during ebullition I gradually add one, 

 two, or even four drops of dilute sulphuric acid. The alcohol, 

 at first colourless, now assumes a red tint, and the albumen, 

 which is deposited upon standing, is either free from colour, 

 or becomes so after being once more boiled in strong alcohol. 

 It must then be boiled several times in alcohol of 0*925, which 

 takes up the sulphate of globulin, and leaves the albumen. ^ 



' As sulphate of albumen is insoluble in alcohol, we need not be apprehensive of 

 losing any albumen by this extraction. I have convinced myself, by a special inves- 

 tigation, that spirit of '925 takes up nothing but sulphate of globulin from the pul- 

 verized residue of the blood. The fluid, while hot, is perfectly clear, but becomes 

 rather turbid on cooling, in consequence of the separation of fat. 



