6 COMPAEISON OF BEEF AND YEAST EXTRACTS. 



show that the purin content of meat and yeast extracts are practically 

 identical, and this agrees with the findings of the writer. There is 

 no conclusive proof of Gamgee's claim that the purin bases of yeast 

 extract are more injurious than those of meat preparations. 



The results reported in Table 1 have been calculated to a fat-free 

 and water-free basis and these figures afford a far more accurate 

 basis for determining the relative values of the two varieties of ex- 

 tracts. On the dry basis the ash of the two yeast extracts and also 

 all of the phosphoric acid figures are higher than for the beef ex- 

 tracts. The total nitrogen and the amino or extractive nitrogen 

 results are far below the beef-extract figures. The chlorin in the 

 ash, the acidity, the proteose and peptone nitrogen, and the purin 

 base nitrogen show no great variations in the* different extracts ex- 

 amined. As the ash determinations were made by placing the sample 

 in the cold muffle and gradually heating to low redness, there is a 

 minimum loss of phosphoric acid, and it is probable that in many 

 cases where the samples for ash are placed directly in a hot muffle a 

 larger per cent of the phosphoric acid is volatilized. Emmett and 

 Grindley state that 23 per cent of the ash of beef consists of phos- 

 phorus. Some experiments made by the writer show that a large part 

 of the phosphoric acid of beef and approximately one-half of the 

 sulphur is soluble in water. The great solubility of the phosphoric 

 acid of beef accounts, of course, for the large amount present in the 

 extracts. 



Lactic acid is a recognized constituent of beef extract. Gamgee ft 

 gives a method for its preparation from Liebig's meat extract. The 

 writer found the characteristic zinc sarcolactate crystals described by 

 Kiihne in a sample of beef extract, but none was found in the yeast 

 extracts. Salkowski c has recently found quite large amounts of 

 inactive lactic acid in a commercial meat juice as magnesium crystals. 

 He holds that the active lactic acid of meat is converted to the inac- 

 tive form on standing. 



The acidity of beef extract is due not only to the lactic acid of 

 the beef, although this is the predominating acid, but also to the 

 acid phosphates and proteins present. The nitrogen results on the 

 water-free and fat-free basis show higher figures for the beef extracts 

 examined than for the yeast preparations. The average figures show 

 11.82 per cent of total nitrogen in the former case and 7.44 per cent in 

 the yeast extracts. The per cent of the amino bodies is much larger, 

 both relatively and proportionally, than in the yeast preparations. 

 The remainder of the nitrogen is present in both extracts as albumoses 



J. Amer. Chem. Soc., 1906, 28 : 56. 



6 Physiol. Chem., 1880, 1 : 361. 



c Zts. physiol. Chem., 1909, 63 : 237. 



