60 PHYSIOLOGICAL CHEMISTRY. 



Serum globulin may be easily separated as a fine floccujent pre- 

 cipitate from blood-serum by neutralizing or making faintly acid 

 with acetic acid and then diluting with 10-20 vols. of water. For 

 further purification this precipitate is dissolved in dilute common - 

 salt solution, or in water by the aid of the smallest possible amount 

 of alkali, and then reprecipitated by diluting with water or by the 

 addition of a little acetic acid. The serum globulin may also be 

 separated from the serum by means of magnesium or ammonium 

 sulphate; in these cases it is difficult to completely remove the salt 

 by dialysis. The serum globulin from blood-serum is always con- 

 taminated by lecithin and the so-called fibrin ferment. A serum 

 globulin free from fibrin ferment may be prepared from ferment- 

 free transudations, as sometimes from hydrocele fluids, and this 

 shows that the serum globulin and the fibrin ferment are different 

 bodies. For the detection and the quantitative estimation of serum 

 globulin we may use the precipitation by magnesium sulphate 

 added to saturation (AUTHOR), or by an equal volume of a saturated 

 neutral ammonium sulphate solution (HOFMEISTER and KAUDER 

 and POHL). In the quantitative estimation the precipitate is col- 

 lected on a weighed filter, washed with the salt solution employed, 

 dried with the filter at about 115 C., then washed with boiling- 

 hot water, so as to completely remove the salt, extracted with 

 alcohol and ether, dried, weighed and burnt to determine the 

 ash. 



Serum Albumin is found in large quantities in blood-serum, 

 blood-plasma, lymph, transudations, and exudations. Probably it 

 also occurs in other animal liquids and tissues. The albumin 

 which passes into the urine under pathological conditions consists 

 largely of serum albumin. 



In the dry state serum albumin forms a transparent, gummy, 

 brittle, hygroscopic mass, or a white powder which may be heated 

 to 100 C. without decomposing. Its solution in water gives the 

 ordinary reactions for albumin; the specific rotary power for serum 

 albumin free from paraglobulin, obtained from human transuda- 

 tions, is, according to STARK, or(D) 62.6 to 64.6. The 

 coagulation temperature of a serum-albumin solution is -f 70 to 

 -j- 75 C., according to most authorities, but this varies to a great 

 extent with a varying concentration and amount of salt. A 1-2$ 

 albumin solution may, in the presence of very little NaCl, coagu- 

 late at + 50 0. or below; in the presence of 5$ NaOl it coagulates 



