1884.] The Proteids of Semm. 105 



6. Another portion was saturated with magnesium sulphate, and 

 the resulting precipitate filtered off ; the filtrate gave precipitates at 

 73, 77, and 83. The precipitate produced by magnesium sulphate 

 after being washed and dissolved was found to coagulate entirely 

 at 75 C. 



Thus it is the albumin of serum and not the globulin which is thus 

 differentiated by heat-coagulation into three several proteids with 

 different temperatures of heat-coagulation. 



Results similar to these, the points varying a degree or two in 

 various cases, were obtained from the serum of the cat, monkey, 

 rabbit, pig, and man. In most instances the blood of several of each 

 of these animals was examined. In one specimen of monkey's serum 

 no coagulum occurred after 77 ; the total amount of proteids in this 

 specimen was, however, very small. In one or two instances a fourth 

 coagulum at 87 88 was found to occur, but this was quite excep- 

 tional. 



In addition to examining the blood-serum of man, the various 

 so-called serous effusions have been submitted to similar analysis. 

 For these I am indebted to Dr. Henry Maudsley, Resident Medical 

 Officer, University College Hospital, and to others of the resident 

 staff there. It may be briefly stated that all gave similar results, 

 viz., that by a process of fractional heat-coagulation the albumin of 

 serum can be differentiated into three separate proteids. The fluids 

 examined have been hydrocele fluid, pleuritic fluid, ascitic fluid, and 

 parovarian fluid. 



Is alkali-albumin a constant constituent of the blood-serum ? In 

 one or two instances neutralisation produced a faint cloudiness, but 

 as a rule it did not. After dilution, neutralisation of the serum was 

 found invariably to produce a precipitate ; excess of acid up to a 

 certain point increased this, then dissolved it; on collecting this 

 precipitate and examining it, it was found to be serum- globulin. 



On making some alkali-albumin artificially from egg-albumin, it 

 was found that magnesium sulphate precipitates it completely, in the 

 same way that that salt precipitates serum-globulin. If alkali- 

 albumin is present in serum, it will therefore be precipitated with the 

 globulin, when the serum is shaken with powdered magnesium 

 'sulphate. This precipitate, however, was found when redissolved to 

 coagulate entirely at 75, and filtering off the coagulum the filtrate 

 showed no evidence of proteid. 



The blood of the sheep, ox, and horse was found to differ from 

 those just described, as in them the serum-albumin can only be 

 differentiated into two proteids by the process of fractional heat- 

 coagulation ; the points at which precipitation occurs being 77 C. 

 and 84 C. 



The albumins of serum having thus been shown to be more numer- 



