398 STATE BOARD OP AGRICULTURE. 



of the determination as all errors due to reading the burette, etc. are 

 cut in two in the final result. 



The Effect of Add on tJie Nitrogenous Compounds of Peat. 



Van Slyke^ has shown that the amount of amino nitrogen formed 

 is a measure of the hydroWsis of protein compounds. He came to this 

 conclusion from the following considerations. From the work of Emil 

 Fischer the combination of amino acids in the protein molecule may be 

 indicated thus, 



HO HO 



H,N— t — 6 N— 6 — C— OH, 



R H R 



the group CONH being known as the "peptid group." The nitrogen 

 in this group is in the imino (NH) form. Upon hydrolysis, each 

 pe})tid group takes up a molecule of water forming a free carboxyl 

 (COOH) group and converting the imino (NH) group into an amino 

 (NHo) group. 



HO HO 



H^N— C— t— OH H— N— 6— 'd— OH 



R H A 



As the hydrolysis of the compound continues, the proportion of nitro- 

 gen in the amino form increases until at complete hydrolysis it reaches 

 a maximum. 



Van Slyke has studied the hydrolysis of various protein compounds 

 by different reagents and obtained results which agree with the theory. 

 In each case the rate of formation of amino nitrogen increased rapidly 

 at first but finally approached a constant maximum value. He ob- 

 tained the following results in the hydrolysis of egg albumen by means 

 of 5 per cent NaOH. 



TABLE I. 



Hours. 



Per cent of 



total 

 nitrogen. 







0.5 



4.5 



25 



48 



96 



144 



Complete hydrolysis. 



3.00 

 7.15 

 19.45 

 34.02 

 46.62 

 61.10 

 68.42 

 85.20 



Upon tre'ating peat with acid a similar change takes place in the 

 amino nitrogen content as is shown by the following table the results 

 of which are shown graphically in Plate I. The peat used in this ex- 



'Ber. d. Deutsch. Cliem. Gesel. 43, 3170; Proc. Soc. Exp. Biol, and Med. 7, 170. (1910). 



