98 TOXINES AND ANTITOXINES. 



antitoxine precipitated together with the zinc on the addition of alkali 

 carbonate or phosphate, though it was carried down with the zinc 

 hydroxide on the addition of an alkali hydroxide. From this precipitate 

 it could be extracted by means of an excess of very dilute alkali, of only 

 sufficient strength to just colour phenolphthalein. A solution of baryta 

 could not be used since it destroyed the antitoxine. Unsatisfactory 

 results were also obtained with iron salts. The solution was then 

 saturated at the ordinary temperature with magnesium sulphate, which 

 precipitated the antitoxine quantitatively. After further extractions with 

 alkali and dialysis the final product was dried in vacua. 



Still better results were obtained by the following method : The serum 

 was first treated with a third of its volume of a 5 per cent, solution of 

 alum. This precipitated the albumins, leaving the whole of the antitoxine 

 in solution. The solution was then filtered and dialysed. The globulins, 

 and with them the antitoxine, were precipitated from the dialysate by 

 semi-saturation with ammonium sulphate, and the precipitate washed 

 with a semi-saturated solution of ammonium sulphate. The precipitate 

 was then redissolved in water and the solution dialysed, concentrated 

 in vacuo, and filtered. 



In this way they obtained from 500 c.c. of serum 9 grms. of a dry 

 preparation in the form of a reddish -brown gelatinous mass. This dis- 

 solved slowly in water (4'7 grms. in 16 c.c.) yielding a syrupy reddish- 

 brown fluid, which readily became turbid and could only be filtered slowly. 

 The filtrate contained the same proportion of antitoxine as the unfiltered 

 preparation. The addition of phenol was not injurious. The preparation 

 behaved like a globulin. 



ASTROS and RiETSCH 1 claim to have separated the antitoxine 

 from the serum almost quantitatively. 



They diluted the therapeutic serum with four parts of water, and then 

 added sufficient sodium chloride and potassium chloride to give a 20 per 

 cent, solution, after which 0'5 per cent, of phenol was added, and the 

 liquid left for twenty-four hours at 33 C. 



The theoretically important experiments of PICK may pos- 

 sibly be also of practical importance. He showed that by 

 saturating the liquid with ammonium sulphate, to the extent 

 of about a third, a part of the globulins without any thera- 

 peutic value was precipitated, whilst the active anti-bodies 

 were separated when the degree of saturation reached 38 to 

 46 per cent. By this means he effected a tenfold to fifteenfold 

 concentration. We will deal presently with the significance of 

 his work. 



Equally important, from the practical point of view, are the 

 experiments of PROSCHER, 2 who claims to have freed the anti- 

 toxines from proteid admixtures by digestion with trypsin. 



1 Astros and Rietsch, "Essais d'Extraction de 1'antitox. diphth. " Soc. 

 BioL, lii., 337, 1900. 



2 Proscher, German Patent, F. 13,756, June 6, 1902. 



