METHODS OF ANALYSIS. 33 



the determination of total phosphorus by the peroxid method," and 

 the separation of the organic from the inorganic phosphorus by the 

 method of Siegfried and Singewald, 6 described under ash. Sodium 

 chlorid was estimated by the Volhard method. 



The methods of the Association of Official Agricultural Chemists 

 were used in most cases. rf For the determination of total nitrogen, 

 total meat bases, xanthin bases, and insoluble and coagulable pro- 

 teids aliquots of one solution of the sample were used. The pep- 

 tones were determined by the tannin-salt method 6 and the kreatinin^ 

 by a modification of Folin's method (page 39). 



Many reagents have been used to separate the meat bases from the 

 nitrogenous bodies of larger molecular weight. Phosphotungstic 

 acid has been more widely employed than any of the others, but is 

 known to precipitate many of the diamido acids,* 7 and its power to 

 precipitate completely the peptones 7 ' is not established. Mallet ' 

 states that the use of phosphotungstic acid as a precipitant, fol- 

 lowed by washing the precipitate with hot water, seems to effect a 

 separation of all the simpler amidic substances from the proteids and 

 proteid-like bodies, excepting only the peptones. Mallet quotes 

 authority to show that the peptones are precipitated by tannic acid. 

 The method was tried in the present investigation, but was discarded. 

 Bromin has been suggested by Allen and Searle^ as a reagent for 

 separating the higher amido bodies from the lower amido acids, but it 

 has been found by Schjerning* and others to be unreliable. That 

 the tannin-salt reagent makes an absolute separation is not claimed, 

 but it seems to be the best at present available. 



Insoluble and Coagulable Proteids. 



In Table XIII figures are given showing the amount of nitrogen 

 present in the insoluble form as distinguished from that present in the 

 coagulable form. This separation was made on seven extracts in- 

 cluded in Table VII (miscellaneous preparations), which showed high 

 coagulable nitrogen figures. The provisional methods l of the Asso- 

 fl J. Amer. Chem. Soc, 1904, 2 6: 1108. 



&2te. Nahr. Genussm., 1905, 10: 521. 



cLiebig's Annalen, 1878, 190:1. 



«*U. S. Dept. Agr., Bureau of Chemistry, Bui. 107. 



e.U. S. Dept. Agr., Bureau of Chemistry, Bui. 99, p. 182. 



/All kreatinin figures refer to kreatinin and kreatin estimated as kreatinin after 

 dehydration. 



g Hammarsten, Physiological Chemistry, 1904, p. 80. 



T. S. Dept. Agr., Bureau of Chemistry, Bui. 73, p. 92. 



I U. S. Dept. Agr., Bureau of Chemistry, Bid. 54, p. 21. 



J Analyst, 1897, ££: 258. 



* Zts. anal. Chem., 1900, 59:545. TJ. S. Dept. Agr., Bureau of Chemistry, Bui. 81, 

 p. 104. 



I U. S. Dept. Agr., Bureau of Chemistry, Bui. 107, p. 115. 



43689— Bull. 114—08 3 



