SPIRITS OF TURPENTINE. 13 



14. Sapoiiification Number. 



Weigh from two to three grains of oil ill a 200 cc Erlenmeyer flask, add 30 cc 

 of a half-normal alcoholic solution of potassium hydroxid, connect with a reflux 

 air condenser, heat on a steam bath for an hour, then titrate with half-normal 

 sulphuric acid, using phenolphthalein as indicator. Always run two blanks 

 with the alcoholic potash. From the difference between the number of cubic 

 centimeters of acid required by the blanks and the determinations, calculate the 

 saponification number (milligrams of potassium hydroxid to 1 gram of oil). 

 The saponiflcation number should be about 190. 



15. TTnsaponifiable Matter. 



As the saponification varies somewhat in pure oil, it is sometimes advisable 

 to make a direct determination of unsaponifiable matter. Saponify from 5 to 

 10 grams of oil with alcoholic potassium hydroxid (200 cc of a half -normal 

 solution) for an hour on a steam bath, using a reflux condenser. Then remove 

 the condenser and evaporate the alcohol as completely as possible ; dissolve the 

 soap in 75 cc of water, transfer to a separatory funnel, cool, shake out with two 

 portions of 50 cc each of gasoline distilled between 35 and 50 C., wash the 

 gasoline twice with water, evaporate the gasoline, and weigh the unsaponifiable 

 matter, which in raw linseed oil should be below 1.5 per cent ; in boiled oil it is 

 somewhat higher, but should be below 2.5 per cent. 



16. lodin Number. 



Weigh in a small glass capsule from 0.2 to 0.25 gram of oil, transfer to a 

 350 cc bottle having a well-ground stopper; dissolve the cil in 10 cc of chloro- 

 form and add 30 cc of Hanus solution ; let it stand with occasional shaking for 

 one hour, add 20 cc of a 10 per cent solution of potassium iodid and 150 cc of 

 water, and titrate with standard sodium thiosulphate, using starch as indicator. 

 Blanks must be run each time. From the difference between the amounts of 

 sodium thiosulphate required by the blanks and the determination, calculate 

 the iodin number (centigrams of iodin to 1 gram of oil). The iodin number of 

 raw linseed oil varies from 175 to 193, though Gill states that a pure raw oil 

 may give a value as low as 160. Boiled oil may be very much lower. 



Make the Hanus solution by dissolving 13.2 grams of iodin in 1,000 cc of 

 glacial acetic acid which will not reduce chromic acid, and adding 3 cc of 

 bromiri. 



17. Rosin or Rosin Oil (Liebennann-Storch Test). 



To 20 grams of oil add 50 cc of alcohol, heat on a steam bath for fifteen min- 

 utes, cool, decant the alcohol, evaporate to dryness, add 5 cc of acetic anhydrid, 

 warm, cool, draw off the acetic anhydrid, and add a drop of sulphuric acid, 1.53 

 specific gravity. Rosin or rosin oil gives a fugitive violet color. 



SPIRITS OF TURPENTINE. 



1. Color. 

 The best quality of spirits of turpentine should be water white. 



If wood turpentine has been carefully refined, it will comply with all the 

 tests given for spirits of turpentine, but it can almost invariably be distin- 

 guished from the latter by its characteristic odor. 



