102 The Nature of Precipitin Reactions 



Linossier and Lemoine, Eisenberg (5, v. '02, p. 291), and Ascoli 

 (26, vni. '02, p. 1410), agree in finding that the supernatant fluid may 

 contain an excess of both interacting bodies in solution after precipitation 

 has taken place. This is proved by adding either the one or the other 

 component to the clear supernatant fluid, which leads in either case 

 to fresh precipitation. 



The Influence of Salts upon the Reaction. 



That concentrated solutions of certain salts impede analogous re- 

 actions, such as those with bacteriolysins (Lingelsheim) and agglutinins 

 (Eisenberg and Volk) has already been observed. Linossier and Lemoine 

 (21, III. '02) taking a 1 : 20 serum dilution and adding increasing amounts 

 of NaCl thereto, found that even the presence of 1 /o salt impeded the 

 precipitin reaction, and that 5 / salt prevented precipitation even after 

 a mixture had stood as long as 24 hours. They found the reaction to take 

 place in the presence of small amounts (1 / ) of ammonium sulphate, 

 magnesium sulphate, and sodium fluoride, as they state was previously 

 noted by Arthus. Eisenberg's (v. '02, p. 307) results are in flat contra- 

 diction ; he states that concentrated NaCl solutions (up to close on 

 18/o, at which point albumins are thrown down) had no influence on 

 the reaction. The reaction was prevented by 0'25 normal magnesium 

 sulphate, slowed by 0'5 magnesium chloride, prevented by a 2-normal 

 solution of the latter salt. Moreover, Rostoski (1902, b. p. 42) observed 

 no noticeable difference in the precipitations which took place with 

 haematosera in the presence of 10 /o NaCl, and 2 "/ ammonium sulphate 

 and ammonium chloride. On the other hand, Miiller (18, n. '02) 

 found the action of lactosera depends upon the presence of lime salts, 

 although these may be replaced by barium salts. Lactoserum only 

 occasionally precipitated boiled milk after the addition of lime salts. 

 Michaelis (9, x. '02, p. 734) removed all trace of lime salts both from 

 haematoserum aud its homologous blood by means of oxalate of 

 potassium and found the contrary, namely, that precipitation occurred 

 as well as before. Rostoski (1902, b. p. 42) on the other hand, also 

 experimenting with haematosera, obtained the same result as Miiller. 

 He states that precipitation does not take place in the absence of salts, 

 small quantities thereof are sufficient, large amounts of NaCl do not 

 impede precipitation. It was evident therefore that these experiments 

 required to be repeated. 



Graham-Smith and ganger (1903, p. 266) undertook to solve this 



