CHEMICAL MECHANICS OF SYNTHESIS 



441 



The filter papers were then thoroughly macerated m dilute 

 potassium hydrate and the magma thus prepared was filtered 

 and washed with distilled water, the filtrate and washings being 

 collected in the beaker which received the first washings with 

 N/IO potassium hydrate. Care was taken to prevent more than 

 a slight excess of acetic acid from being finally present in this 

 beaker. The precipitate which formed in the beaker settled rapidly 

 in small flocculi, was collected upon a soft rapid-filtering paper 

 and thoroughly washed with distilled water until the washings 

 were neutral to htmus. In all cases the filtrates and washings 

 were perfectly clear and free from protein. The papers and 

 precipitates thus obtained were macerated in water containing 

 a known quantity (10 cc.) of N/10 potassium hydrate, the magma 

 thus obtained was diluted to about 200 cc, phenolphthalein 

 (4 drops of 2 per cent alcoholic solution) was added and the solu- 

 tions thus prepared were titrated to neutrality with N/IO hydro- 

 chloric acid. A weighed amount (227 milligrams) of paranuclein 

 A prepared in the manner described in section 1 was dissolved in 

 about 100 cc. of distilled water containing exactly 10 cc. of A^/10 

 potassium hydroxide, and the solution was titrated to neutrality 

 with iV/10 hydrochloric acid and phenolphthalein indicator; in 

 this way it was found that 1 gram of paranuclein A neutralizes 

 4.8 cc. of iV/10 potassium hydroxide*; hence 1 cc. of N/10 alkah 

 = 0.208 gram of paranuclein A and we can estimate from the 

 determinations described above the amount of paranuclein A 

 produced in each of the mixtures by varying amounts of pepsin. 

 The following were the results obtained : 



* I have found that upon standing in the presence of excess of alkali, the 

 amount of alkah neutralized by a given quantity of paranuclein A increases 

 shghtly. I have been unable to determine whether this phenomenon is due to 

 the slow dissolving of microscopic suspended particles or whether it is due to 



