BY JAMES M. PETRIE. 



843 



The following experiment was designed to determine the 

 maximum possible amount of non-precipitable nitrogen by succes- 

 sive extraction with dilute salt solution till no more was dissolved. 



From the same stock of A. pycnantha, the age of which was 

 a,bout two years, a sample was taken, ground in a mill, and well 

 mixed. This contained 4*5 % of N; 20 gms. were extracted for 

 one day in the cold, with 1 litre of 10 °/o salt solution, and filtered. 

 The residue was treated in the same way four times, then ground 

 still finer, and the extraction repeated, till at the eighth time 

 practically no nitrogen was found in the solution. In each of 

 the eight salt extracts the proteins were precipitated by 10 °/o 

 tannin solution in slight excess; the nitrogen in the original 

 solution and in the tannin precipitate was determined. 



20 gms. seeds extracted with salt solution, and extracts pieci- 

 tated by tannin. Results— 





fraction 



N in tannin 



ppt. gm. 



(b) 



N in tannin 



filtrate gm. 



(a-b) 



Total 



N gm. 



(a) 



1st ej 



0-2585 

 0375 

 0-0308 

 0-0154 

 0066 

 0-0090 

 0024 

 trace 



0-3230 

 0680 

 00127 

 00014 



nil 



nil 



nil 



nil 



05815 



9x\<\ 





01055 



3rd 



" 



0*0435 



4th 



5th 



>> 



0-0168 

 0066 



6th 



7th 

 •8th 



>> 



>> 



0-0090 

 0-0024 

 trace 





Total N extracted 







0-3602 

 1360 



4051 



0-7653 





N in exhausted resd 



0*1360 









N in orig. 20 gms. seeds (4 "50%). 



0-9013 

 0-9000 



This series of results shows that all the non-protein nitrogen 

 is extracted after four successive treatments, and that it amounts 

 to 2 gms.^o of the seeds, as against \'l°/o obtained by alcohol in 

 the previous series. Of the nitrogen extracted by salt solution 

 53^o or more than half is non-protein; and finally the amount of 

 non-protein nitrogen, as represented by the part not precipitable 



