56 PROVISIONAL METHODS FOE ANALYSIS OF FOODS. 



7. DETERMINATION OF LIME. 



Calcium sulphate and carbonate are frequently used as adulterants, and are also 

 present in appreciable amount in limed nutmegs, ginger, etc. In the presence of 

 calcium sulphate, the water solution gives tests for both lime and sulphuric acid. 

 Samples containing a considerable amount of carbonate effervesce on addition cf 10 

 per cent hydrochloric acid. Determine lime in the ash, after separation of iron and 

 alumina phosphates, as described under Baking Powder (p. 106.) 



8. DETERMINATION OF TOTAL SULPHUR. a 

 (For mustard and samples adulterated with calcium sulphate.) 



Convert about 10 grams of sodium peroxid into hydroxid in a nickel crucible by 

 adding a little water and boiling over a low flame until the excess of water is 

 expelled. Stir 1 gram of the material into the slightly cooled hydroxid and oxidize 

 by gradually raising the heat and adding small portions of sodium peroxid until 

 the oxidation is complete. Dissolve the fused mass in 400 cc of water, acidify 

 strongly with hydrochloric acid, boil until the excess of peroxid is destroyed and 

 chlorin expelled, filter through pure paper, make neutral with ammonia, and add 

 an excess of 4 cc of concentrated hydrochloric acid. From the boiling solution pre- 

 cipitate sulphuric acid by gradually adding a solution containing 1 gram of barium 

 chlorid. After standing over night, in a warm place, filter the barium sulphate, 

 wash, ignite, and weigh. 



Osborne has found commercial sodium peroxid to be freer from sulphur than 

 most preparations of so-called chemically pure sodium hydroxid made from the metal, 

 and as the former is very much cheaper than the latter, it is advantageous to use it 

 as here described. 



9. DETERMINATION OF CARBON DIOXID. 



( For samples adulterated with calcium carbonate. ) 



Proceed as directed under total carbon dioxid in Baking Powder (p. 98 and 

 following). 



10. DETERMINATION OF VOLATILE AND NONVOLATILE ETHER EXTRACT. b 



Extract 2 grams of the ground material for 20 hours, in a continuous extraction 

 apparatus, with absolute ether. c Transfer the ethereal solution to a tared capsule 

 and allow to evaporate at room temperature. Let stand 18 hours over sulphuric acid 

 and weigh the total ether extract. Heat the extract gradually to 100 C. , continue the 

 heating at that temperature for 6 hours, and then at 110, until the weight becomes 

 constant. The loss is volatile oil; the residue, nonvolatile ether extract. 



11. DETERMINATION OF ALCOHOL EXTRACT. d 



Place 2 grams of material in a 100-cc flask and fill to the mark with 95 per 

 cent alcohol by volume (sp. gr. 0.815 at 15.5 C. ). Stopper, shake at intervals of 30 

 minutes for 8 hours, and allow to stand 16 additional hours without shaking. Filter 

 the extract through a dry filter, evaporate 50 cc to dryness in a flat-bottomed dish 

 on a water bath, and heat to constant weight at 110 C. The result is practically the 

 same when the time of extraction is 48 instead of 24 hours. Win ton, Ogden, and 

 Mitchell, c who describe this method, do not claim that it extracts all matter soluble 

 in alcohol; in fact, the residue separated from the solutions by filtration, when 



Osborne, Conn. Agr. Expt. Sta. Kept., 1900, p. 445. 



b Richardson, U. S. Dept. ot Agr., Div. of Chem., Bui. 13, Part 2, p. 165. 



c See Appendix, pp. 153 and 154. 



d See Appendix, p. 154. 



Conn. Agr. Kxpt. Sta. Ilcjt., ISM, p. 187. 



