114 



Tim chloride. Peckholt obtained by tbis process 7*848 per cent, of a 

 wbite, light amorphus powder which he called " papayotin." 



(2) Mix the juice with four times its weight of water ; filter, and 

 precipitate with alcohol (95 per cent.) ; \s ash and dry the precipitate. 

 This gives 3 "762 per cent, of a product practically the same as (1) but 

 not quite so light. 



(8) Evaporate the latex to dryness and then completely exhaust 

 with ether and alcohol (absolute), as in the first method. Dissolve 

 the residue in water and precipitate with alcohol. The result being a 

 light brown powder of which Peckholt obtained 5*338 per cent. (He 

 called this '* parapayotin.") 



(4) Wurtz prepared the ferment as follows : The milky juice 

 was thrown on a filter and the coagulum washed with water The 

 aqueous solution then obtained was reduced to a small volume in a va- 

 cuum, and was precipitated by ten times its volume of alcohol. This 

 precipitate was dried, dissolved in water and precipitated a second time 

 with alcohol, washed with absolute alcohol and dried in a vacuum. 

 The product of this process he called " papain." 



(5) A method now in actual use in one of the West India Islands is 

 as follows : Pour into the strained latex five times its volume of 

 full strength alcohol, collect the precipitate and wash with absolute 

 alcohol; dry over calciuin chloride or sulphuric acid. (Thi re is a con- 

 siderable loss of alcohol ; the product is small, fairly autive, but high 

 priced.) 



(6) Method devised by the author : Dry the latex without heat ; 

 exhaust the dry residue first with ether, then with chloroform, followed 

 by benzine ; finally extract with alcohol. Under this process, if the 

 extraction is thoroughly carried out, everything is removed except the 

 proteids and ash. The product is a fine grey-white amorphus powder 

 almost completely soluble in water, more active and more nearly lepre- 

 sentativeof the peculiar properties of the latex than the product result- 

 ing from any other method which has come under observation.- 



(7) Salt-precipitation method. The well-known methods of preci- 

 pitation by alkaline salts are applicable to the separation of the papaw 

 ferments. The latex diluted with water or the dried latex extracted 

 with water (filtered), when saturated with sodium chloride, with am- 

 monium sulphate or with magnesium sulphate, will yield a heavy 

 precipitate of the proteid contents carrying the greater portion of the 

 ferments. Such precipitates may be freed from salts by subjecting their 

 solution to dialysis, the resulting solution (and precipitate residue) are 

 then to be evaporated to dryness. 



The yield from these salt-precipitation methods is s:nall, but. if the 

 processes are carefully performed, furnish a satisfactery product, weaker 

 however in action than those perpared by the method outlined in the 

 preceding section. 



Something like thirty methods for separation have been tried in my 

 researches, with the result thut all methods where precipitation is in- 

 volved, tend to weaken the digestive power of the ferment. The me- 

 thods used in the separation of pepsin whereby a purified and high 

 power pepsin is produced, are as follows : Digestion of the proteid 

 constituents, precipitation and purification of the product do not seem 

 to be applicable to the papaw. 



