XXIV] SPICES AND OTHER CONDIMENTS 321 



granules, dissolves the proteins, saponifies the fats, and in other ways clears the 

 preparation. It also imparts to tannins a reddish color. If this treatment does 

 not clear the tissues satisfactorily, treat a fresh portion for some hours with the 

 chloral hydrate solution. 



Examine also the crude fiber obtained in the chemical analysis, as in this mate- 

 rial the stone cells and other tissues are shown distinctly. 



To isolate stone cells, bast fibers and other thick-walled cells macerate a por- 

 tion of the sample in Schultze's mixture, using such proportion of potassium chlor- 

 ate and nitric acid and heating for such a time as secures the desired results. Pow- 

 dered charcoal and charred shells resist the bleaching action of potash, chloral 

 hydrate and Schultze's mixture. 



If it is desired to distinguish cellulose from infiltrated substances (lignin, suberin, 

 etc.), add the freshly prepared chlor-zinc iodin solution to a water mount, whereby 

 the former is colored blue and the latter yellow. 



Test for proteins by cautiously warming on a slide with a drop of freshly pre- 

 pared Millon's reagent. The proteins are partially decomposed, acquiring grad- 

 ually a brick-red color. If it is desired to study the form of the aleurone (pro- 

 tein) granules, which in some plants are quite as characteristic as starch granules, 

 prepare a mount in pure glycerol or oil. 



To distinguish fats, oils, essential oils and resins from other cell contents, treat 

 for an hour with the alkanna tincture, diluted with an equal bulk of water, which 

 imparts to these substances a deep red color, or treat with ether, which dissolves 

 them. Treat also with alcohol, which dissolves the essential oils and resins, but 

 does not perceptibly affect the fats and oils. 



In testing for tannins and tissues impregnated with these substances, add the 

 1% ferric acetate or chlorid solution. Both of these reagents give a green or blue 

 color with tannins, but the former acts more slowly and is to be preferred. 



Crystals of calcium oxalate are recognized by their characteristic forms and 

 their behavior to polarized light. To distinguish calcium oxalate from calcium 

 carbonate, treat with acetic acid, which does not affect the former, but dissolves 

 the latter with effervescence. Both arc soluble in hydrochloric acid. 



PREPARED MUSTARD. 



23 PREPARATION OF SAMPLE.-TENTATIVE. 



Transfer the entire contents of the container to a dish sufficiently large to stir 

 thoroughly and make the whole mass homogeneous. Preserve in a bottle having 

 a tightly fitting glass stopper. Stir well each time before removing a portion for 

 analysis. 



24 SOLIDS.-TENTATIVE. 



Weigh 5 grams of the sample into a flat-bottomed, platinum dish, distribute 

 evenly over the bottom of the dish with a little water, place on a water bath until 

 the mixture appears dry, and heat finally to constant weight at 100°C. in a water 

 oven. 



25 ASH.-OFFICIAL. 



Ignite the dry residue, obtained in the determination of solids, 24, as directed 

 under VIII, 4. 



26 SALT.-TENTATIVE. 



Determine chlorin in the ash as directed under III, 15. 



