36 MEAT EXTRACTS. 



but the soluble forms (glutin and gelatoses) are present, being formed 

 by action of the lactic acid on the gelatin. 



The following tentative standard has been framed by the food 

 standards committee: 



Gelatin (edible gelatin) is the purified, dried, inodorous product of the hydrolysis, by 

 treatment with boiling water, of certain tissues, as skin, ligaments, and bones, from 

 sound animals, and contains not more than two (2) per cent of ash and not less than 

 fifteen (15) per cent of nitrogen. 



EXPERIMENTAL WORK ON METHODS. 



Experiments were made to test the following gelatin methods: 



(1) the Stutzer ice- water alcohol method, modified by Bigelow; 6 



(2) theBeckmann c formaldehyde method; (3) the trichlor-acetic-acid 

 method of Obermayer. d 



The gelatin used in these experiments was a product of good 

 quality used in preparing culture media. With Millon's reagent it 

 gave a faint pink reaction in the cold, and upon heating a red color 

 developed, showing some proteid matter was present. This reaction 

 shows the presence of tyrosin, and as pure gelatin contains no tyrosin, 

 a small amount of proteid must have been present as an impurity. 

 The biuret test gave a faint reaction with the gelatin solution. 



The solution of gelatoses and gelatin peptones used was prepared 

 by treating some of the gelatin with weak (3 or 4 per cent) hydro- 

 chloric acid for four days on the steam bath. This solution also 

 gave the Millon and biuret tests. Neither the gelatin nor gelatose 

 solutions showed signs of gelatinizing. The former was of 1.14 per 

 cent and the latter of 0.64 per cent strength. 



The modified Stutzer method gives, in the case of pure gelatin 

 solutions, a rough approximation of the amount present, the results 

 showing that about 84 per cent are recovered. With a solution of 

 gelatoses and gelatin peptones, this method gives about 3.6 per cent 

 of the nitrogen present as gelatin nitrogen. This may be due to a 

 trace of gelatin in the gelatose solution. In the case of Witte's pep- 

 tone 19 per cent of the total nitrogen appears as gelatin nitrogen 

 according to the modified Stutzer method. It seems that the abso- 

 lute alcohol precipitates a portion of the albumoses present in Witte's 

 peptone. In the case of the meat extract used, 3.7 per cent of the 

 nitrogen is estimated as gelatin nitrogen by this method. Mixtures 

 of gelatin with gelatoses, Witte's peptone, and meat extract were 

 made in various combinations; also mixtures of the meat extract, 

 Witte's peptone, and gelatose without gelatin. The results for gela- 



aZts. anal. Chem., 1895, 54:568. 



&U. S. Dept. Agr., Bureau of Chemistry, Bui. 107, p. 116. 



c Analyst, 1895, 20:44. 



d Zts. anal. Chem., 1890, 29 : 114. 



