268 METHODS OF ANALYSIS [Chap. 



GINGER. 



51 Seeker Method. — Tentative. 



Dilute 10 cc. of the extract to 30 cc, evaporate to 20 cc, decant into a separa- 

 tory funnel and extract with an equal volume of ether. Allow the ether to evaporate 

 spontaneously in a porcelain dish, and to the residue add 5 cc. of 75% sulphuric acid 

 and about 5 mg. of vanillin. Allow to stand 15 minutes and add an equal volume 

 of water; in the presence of ginger extract an azure blue color develops. 



CAPSICUM. 



52 La Wall Method Modified by Doyle. — Tentative. 



To 10 cc. of the extract add cautiously dilute sodium hydroxid solution until the 

 solution reacts very slightly alkaline with litmus paper. Evaporate at about TO'C. 

 to approximately one fourth the original volume, render slightl}^ acid with dilute 

 sulphuric acid, testing with litmus paper. Transfer to a separatory funnel, rinsing 

 the dish with water, and extract with an equal volume of ether, avoiding emulsi- 

 fication by shaking the funnel gently 1-2 minutes. Draw off the lower layer and 

 wash the ether extract once with about 10 cc. of water. Transfer the washed ether 

 extract to a small evaporating dish, render decidedly alkaline with N/2 alcoholic 

 potassium hydroxid and evaporate at about 70°C. until the residue is pasty; then 

 add about 20 cc. more of N/2 alcoholic potash and allow to stand on a steam bath 

 until the gingerol is completely saponified (about 30 minutes). Dissolve the residue 

 in a little water and transfer with water to a small separatory funnel. The volume 

 should not exceed 50 cc. Extract the alkaline solution with an equal volume of 

 ether. Wash the ether extract repeatedly with small amounts of water until no 

 longer alkaline to litmus. Transfer the washed extract to a small evaporating dish, 

 and allow the ether to evaporate spontaneously. Finally test the residue for capsi- 

 cum by moistening the tip of the finger, rubbing it on the bottom and sides of the 

 dish, and then applying the finger to the end of the tongue. A hot, stinging or 

 prickly sensation, which persists for several minutes, indicates capsicum or other 

 foreign pungent substances. 



PEPPERMINT, SPEARMINT AND V/INTERGREEN EXTRACTS. 



53 ALCOHOL.— TENTATIVE. 

 Proceed as directed under 41 . 



OIL. 



54 Howard Method^'' Modified. — Tentative. 



Pipette 10 cc. of the extract into a Babcock milk bottle, add 1 cc. of carbon di- 

 sulphid, mix thoroughly, then add 25 cc. of cold water and 1 cc. of concentrated 

 hydrochloric acid. Close the mouth of the bottle and shake vigorously; centrif- 

 ugalize for 6 minutes and remove all but 3-4 cc. of the supernatant liquid, which 

 should be practically clear, by aspirating through a glass tube of small bore. 

 Connect the stem of the bottle with a filter pump, immerse the bottle in water kept 

 at approximately 70°C. for 3 minutes, remove from the bath every 15 seconds and 

 shake vigorously. Continue in the same manner for 45 seconds, using a boiling water 

 bath. Remove from the bath and shake while cooling. Disconnect from the suc- 

 tion and fill the bottle to the neck with saturated salt solution at room temperature, 

 centrifugalize for 2 minutes and read the volume of the separated oil from the top 

 of the meniscus. Multiply the reading by 2 to obtain the per cent of oil by volume. 



