264 METHODS OF ANALYSIS [Chap. 



Stopper the flask and mix the contents thoroughly. Pipette 2 cc. of this solution 

 into a colorimeter tube; add 10 cc. of the meta-phenylendiamin hydrochlorid solu- 

 tion and complete the volume to 50 cc. (or other standard volume) with alcohol. 

 Compare at once the color with that of the standard, prepared at the same time, 

 using 2 cc. of standard citral solution and 10 cc. of the meta-phenylendiamin hy- 

 drochlorid solution, and making up to standard volume with alcohol. From the 

 result of this first determination, calculate the amount of standard citral solution 

 that should be used in order to give approximately the same citral strength as the 

 sample under examination; then repeat the determination. 



29 TOTAL SOLIDS.— OFFICIAL. 



Proceed as directed under XVII, 5, employing 10 cc. of the sample measured 

 at 20°C. 



27 ASH.-OFFICIAL. 



Ignite the residue from 10 cc. of the extract as directed under VIII, 4. 



28 SUCROSE.— TENTATIVE. 



Neutralize the normal weight of the extract, evaporate to dryness, wash several 

 times with ether, dissolve in water and determine as directed under VIII, 14 or 18. 



29 METHYL ALCOHOL.— TENTATIVE. 



Proceed as directed under XVII, 16, 17 or 18, using the distillate from the 

 determination of alcohol, 18. 



Coloring Matters. 



30 general.-tentative. 

 Proceed as directed under XI. 



3-1 lemon and orange peel color. 



Albrech Method. — Tentative. 

 Place a few cc. of the extract in each of 2 test tubes; to one, add slowly 3-4 vol- 

 umes of concentrated hydrochloric acid; to the other, several drops of concentrated 

 ammonium hydroxid. If the color is due to lemon or orange peel only it is materi- 

 ally deepened by such treatment. 



LEMON AND ORANGE OILS. 



32 specific gravity.-tentative. 

 Determine the specific gravity at -^ by means of a pycnometer. 



33 INDEX OF REFRACTION.— TENTATIVE. 



Determine the index of refraction with any standard instrument, making the 

 reading at 20°C. 



34 OPTICAL ROTATION.-TENTATIVE. 



Determine the rotation at 20°C. with any standard instrument, using a 50 mm. 

 tube and sodium light. The results should be stated in angular degrees on a 100 

 mm. basis. If instruments having the sugar scale are used, the reading on orange 

 oils is above the range of the scale, but readings may be obtained by the use of 



