G, Williams 209 



minutes. The mixture was then filtered, the filtrate being quite clear 

 and only slightly coloured. The black residue on the filter composed 

 of undissolved slaked Hme and humin bodies was thoroughly washed. 

 . The filtrate and washings were evaporated down under reduced pressure 

 at 40° C. 



Precipitation of the calcium salts of aspartic and glutaminic acids. 



The concentrated residue of the calcium salts of the amino-acids 

 was diluted to a mobile liquid with distilled water, about 100 c.c. 

 being used. Alcohol (98 per cent.) was now added carefully with 

 constant shaking. A precipitate was at once formed, a Httle gummy 

 matter adhering to the bottom of the flask. Alcohol was added until 

 no further precipitate was produced. This was then filtered off and 

 thoroughly washed with alcohol. 



Treatment of the precipitated calcium salts. 



The white precipitate was dissolved in water (any particles remaining 

 in the flask were also dissolved out in water) and the calcium removed 

 quantitatively by means of oxalic acid solution. The clear filtrate was 

 then treated with silver sulphate solution in order to remove traces of 

 hydrochloric acid ; the excess of silver was removed by hydrogen 

 sulphide. The solution was concentrated and cold aqueous phospho- 

 tungstic acid solution added until no further precipitate Avas produced. 

 This removes some bases precipitated by alcohol along with the calcium 

 aspartate and glutaminate. The excess of phosphotungstic acid and 

 the sulphuric acid (from the silver sulphate) were removed quantitatively 

 by means of baryta. The clear filtrate, free from mineral acids and 

 bases, was then evaporated down to dryness. The dry residue weighed 

 7-923 grms. 



Extraction with acetic acid. 



The dry residue was ground up to a fine powder and extracted with 

 cold glacial acetic acid. The acetic acid removes a gummy impurity 

 which contains practically no amino nitrogen. The dry residue insoluble 

 in acetic acid weighed 3-342 grms. This residue was white and consisted 

 of a mixture of glutaminic and aspartic acids. A combustion of this 

 substance was now made. 



0-1236 grm. gave 0-1697 grm. COg and 0-0643 grm. HgO 

 = 37-44 per cent. C and 5-78 per cent. Hg. 



