METHODS OF ANALYSIS. 31 



SEPARATION OF ORGANIC AND INORGANIC PHOSPHORUS. 



The 10:1 ratio of total phosphoric acid to organic phosphoric acid 

 suggested by Siegfried and Singewald a is not constant. This method 

 should be further investigated before applying it to all extracts and 

 food products in general. The high inorganic phosphoric acid con- 

 tent in some cases might be explained by the fact that phosphates 

 may have been added, but we should hardly expect this in the case 

 of organic phosphorus. 



The method of Siegfried and Singewald for the separation of the 

 organic from the inorganic phosphorus was applied to meat extracts 

 in the following manner: 



Dissolve an amount of the original sample corresponding to 10 

 grams of the water-free material in water in a 300 cc flask. Add 50 cc 

 of barium chlorid (10 per cent solution) and 10 cc of ammonia (10 

 per cent solution) . Make the solution up to the mark and thoroughly 

 shake. Allow to stand and employ an aliquot of 250 cc of the filtrate 

 for the estimation of phosphorus by the peroxid method to obtain 

 the amount of phosphorus present in organic form. This figure sub- 

 tracted from the amount of total phosphorus gives the amount of 

 phosphorus in the inorganic form. The accuracy of the method is 

 questionable as the filtrate in the majority of cases was cloudy, and 

 sometimes the slow filtration renders the method extremely tedious. 



ACIDITY. 



In the average solid or pasty extract the lactic acid content varies 

 from 4 to 8 per cent, and, as a rule, the extract showing the highest 

 phosphoric acid content likewise shows the highest acidity. This is 

 undoubtedly due to the fact that some of the phosphoric acid is in 

 the form of dihydrogen or acid phosphate, although the character of 

 the acidity has not been definitely determined. 



The method employed for determining acidity consisted in adding 

 tenth-normal sodium hydroxid to a dilute solution of the meat 

 extract in water until a drop removed by means of a small capillary 

 tube and tested on a piece of litmus paper gives a neutral reaction. 

 The results are expressed in cubic centimeters of tenth-normal 

 sodium hydroxid, also as per cent of lactic acid present. It is recog- 

 nized that the acidity of meat extracts is due to various causes, but 

 lactic acid is the predominating acid, and the results for acidity are 

 usually expressed in the case of such products as per cent of lactic 

 acid. (See Tables I, III, and IX.) 



<*Zts. Nahr. Genussm., 1905, 10\f>2\. 



