XXIII] TATS AND OILS 313 



RESIN OIL, 



35 Qualitative Test. — Tentative. 



Polarize the pure oil, or a definite dilution with petroleum ether, in a 200 mm. 

 tube. Resin oil has a polarization in a 200 mm. tube of from + 30° to + 40° on the 

 sugar scale (Schmidt and Haensch) while most oils" read between + 1° and —1°. 



COTTONSEED OIL. 



36 Halphen TesV*.— Official. 



Mix carbon disulphid, containing about 1% of sulphur in solution, with an equal 

 volume of amyl alcohol. Mi.x equal volumes of this reagent and the oil under ex- 

 amination, and heat in a bath of boiling, saturated brine for 1-2 hours. In the 

 presence of as little as 1% of cottonseed oil, a characteristic red or orange-red color 

 is produced. 



Lard and lard oil from animals fed on cottonseed meal will give a faint reaction; 

 their fatty acids also give this reaction. 



The depth of color is proportional, to a certain extent, to the amount of oil pres- 

 ent, and by making comparative tests with cottonseed oil some idea as to the 

 amount present can be obtained. Different oi's react with different intensities, and 

 oils which have been heated from 200°-210°C.i5 react with greatly diminished in- 

 tensity. Heating 10 minutes at 250°C. renders cottonseed oil incapable of giving 

 the reaction^^. 



PEANUT OIL. 



37 Modified Renard Tesl^^. —Tentative. 



Weigh 20 grams of the oil into an Erlenmeyer flask. Saponify with alcoholic 

 potash solution, neutralize exactly with dilute acetic acid, using phenolphthalein 

 as an indicator, and wash into an 800-1000 cc. flask containing a boiling mixture of 

 100 cc. of water and 120 cc. of 20% lead acetate solution. Boil for a minute and 

 then cool the precipitated soap by immersing the flask in water, occasionally 

 giving it a whirling motion to cause the soap to stick to the sides of the flask. After 

 the flask has cooled, decant the water and excess of lead acetate solution and wash 

 the lead soap with cold water and 90% alcohol by volume. Add 200 cc. of ether, 

 cork and allow to stand for some time until the soap is disintegrated; heat on a 

 water bath, using a reflux condenser, and boil for about 5 minutes'*. In the case of 

 oils, most of the soap will be dissolved, while in lards, which contain much stearin, 

 part of the soap will be left undissolved. Cool the ether solution of soap to 15°- 

 17°C. and allow to stand until all the insoluble soaps have separated out (about 12 

 hours). 



Filter upon a Biichner funnel and thoroughly wash the insoluble lead soaps 

 with ether. Wash the ether-insoluble lead soaps into a scparatory funnel by means 

 of a jet of ether, alternating at the end of the operation, if a little of the soap sticks 

 to the paper, with hydrochloric acid (1 to 3). Add sufficient hydrochloric acid (1 to 3) 

 so that the total volume of the latter amounts to about 200 cc. and enough ether to make 

 the total volume of it 1.50-200 cc. and shake vigorously for several minutes. Allow the 

 layers to separate, run off the acid layer, and wash the ether once with 100 cc. of dilute 

 hydrochloric acid and then with several portions of water until the water washings 

 are no longer acid to me^^hyl orange. If a few undecomposed lumps of lead soap re- 

 main (indicated by solid particles remaining after the third washing with water), 

 break these up bj' running off almost all the water layer and then a add little concen- 

 trated hydrochloric acid, shake and then continue the washing with water as before. 



