HYDROLYSIS 1 1 



(b) Hydrolysis with Sulphuric Acid. 



The protein is hydrolysed by boiling for fifteen to twenty-four 

 hours with six times its quantity of 25-33 per cent, sulphuric 

 acid, or with a mixture of three times its weight of concentrated 

 sulphuric acid and six times its weight of water under a reflux con- 

 denser. Generally, the mixture is heated for one to one and a half 

 hours on a water-bath until frothing has ceased and then in an oil- 

 bath at 105 for the necessary length of time. 



(c) Comparison of the Hydrolysis with Hydrochloric and 

 Sulphuric Acids. 



Several observers have maintained that the results obtained by 

 hydrolysing with concentrated hydrochloric acid and with 25-33 per 

 cent, sulphuric acid are different, but investigations by Abderhalden 

 and Funk [1907] and by Skraup and Turk [1909] have proved that 

 complete hydrolysis is effected by both acids, if the boiling be con- 

 tinued for a sufficiently long time. 



(d) Hydrolysis with Hydrofluoric Acid. 



Hugounenq and Morel [1908; 1909, I ; 1909, 2], who have em- 

 ployed hydrofluoric acid, found that the results depend on the strength 

 of the acid ; the stronger the acid the greater is the amount of com- 

 plex polypeptides. Many hours' boiling with dilute acid are required 

 to effect complete hydrolysis. 



(e) Hydrolysis with Alkalies. 



Proteins are not generally hydrolysed by boiling with alkali. 

 Alkali hydrolysis is only used for special purposes. The amino acids 

 produced are completely racemised, whereas acids cause only partial 

 racemisation. Arginine is destroyed t by boiling with alkali and con- 

 verted into ornithine and ammonia. Cystine is also decomposed by 

 boiling with alkali. 



(/) Comparison of the Hydrolysis with Acids and Alkalies. 



Abderhalden, Medigreceanu and Pincussohn ,[1909] compared 

 the hydrolysis by acids and alkalies. Alkalies produce the most com- 

 plete hydrolysis. Abderhalden and Brahm [1909] found that a body, 

 formed from silk, and resistant to hydrolysis by acid, could only be 

 completely hydrolysed by alkali. 



