308 THE CHEMISTRY OF BLOOD, I., 



Experimental. — The preparation of glohin from ox-blood by 



Lawrows method * 



The Lawrow method is briefly as follows. An aqueous solution 

 of hsemoglol)in is poured, with constant agitation, into a large 

 excess of a mixture of five parts of alcohol, two parts ether, and 

 one water, the mixture having been rendered of such an acidity 

 that lOOcc. contain 0-025 grams HoSO^. It is necessary to add 

 the haemoglobin sohition with care, otherwise the precipitate is 

 likely to be contaminated with undecomposed haemoglobin which 

 is difficult to remove by washing. This dittieulty can, however, 

 be readily overcome by using a much larger excess of sulphuric 

 acid than was employetl by Lawrow. 



In the application of Lawrow's method to the precipitation of 

 ox-blood globin, it is necessary, on account of the greater basicity 

 of the globin, to employ more sulphuric acid, as will be seen from 

 the following experiment. 



Experiment 1. 



Alcohol lOOOcc. 



Ether 400cc. 



Water l-20cc. 



H„SO, N/10 80cc. 



To this mixture were added 50cc. of blood-solution containing 

 the hfemoglobin from exactly 25cc. of defibrinated ox-blood. The 

 solution was thoroughly shaken during the addition of tlie haemo- 

 globin in a stoppered bottle, and the flocculent white precipitate 

 allowed to settle. Of the haemoglobin solution, oOcc. more were 

 now cautiously added, with constant shaking; the precipitate 

 which formed was of deep red colour, and moreover the solution 

 did not darken as before, indicating that the further quantity of 

 haemoglobin had not been decomposed. A portion of the super- 

 natant fluid was tested, and found almost neutral to methyl 

 orange, and neutx'al to dimethylamidoazobenzol, but acid to 

 phenolphthalein. Moreover, on addition of a large excess of 

 sulphuric acid, the precipitated haemoglobin was immediately 

 split, the haematin dissolving and darkening the solution, and the 

 red colour of the precipitate giving place to the white of the 



* H. S. Zeit. Physiol. Chein. Bd. 26, S. 343, 1898. 



