Page 32, under " 16. Halphen Reaction for Cotton-Seed Oil," third 

 line, before the word "brine" insert the word "saturated," and for 

 "fifteen minutes" substitute "an hour to two hours." The second 

 sentence then reads as follows: 



Mix equal volumes of this reagent and the oil under examination and heat in a 

 bath of boiling saturated brine for an hour to two hours. 



Page 33, under " 18. Renard's Test for Peanut Oil as Modified by 

 Tolman," substitute the following (the change made consists in taking 

 20 grams of fat for analysis instead of 5, and increasing proportionally 

 the reagents used as well as providing for an additional washing): 



18. RENARD'S TEST FOR PEANUT OIL AS MODIFIED BY TOLMAN. 



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

 neutralize exactly with dilute acetic acid, using phenolphthalein as indicator, and 

 wash into a 500-cc flask containing a boiling mixture of 100 cc of water and 120 cc 

 of a 20 per cent lead acetate solution. Boil for a minute, and then cool the precipi- 

 tated 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, the 

 water and excess of lead can be poured off and the soap washed with cold water and 

 with 90 per cent (by volume) alcohol. Now add 200 cc of ether, cork the flask, 

 and allow to stand for some time until the soap is disintegrated, then heat on the 

 water bath, using a reflux condenser, and boil for about 5 minutes. & In the oils 

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

 part will be left undissolved. Cool the ether solution of soap down to from 15 to 

 17 C., and let stand until all the insoluble soaps have crystallized out about twelve 

 hours are required. 



aComp.rend., 1871, 73: 1330; Benedikt and Lewkowitsch, Oils, Fats, and Waxes, p. 365. 

 b Process used by N. J. Lane in his modification of Muter's method, J. Am. Chem. Soc., 1893, 

 15: 110. 



Filter and thoroughly wash the precipitate with ether. Save the filtrate for the 

 determination of the iodin number of the liquid fatty acids by the Muter method. 

 The soaps on the filter are washed back into the flask by means of a stream of hot 

 water acidified with hydrochloric acid. Add an excess of dilute hydrochloric acid, 

 partially fill the flask with hot water, and heat until fatty acids form a clear, oily 

 layer. Fill the flask with hot water, allow the fatty acids to harden and separate 

 from the precipitated lead chlorid; wash, drain, repeat washing with hot water, and 

 dissolve the fatty acids in 100 cc of boiling 90 per cent (by volume) alcohol. Cool 

 down to 15 C., shaking thoroughly to aid crystallization. From 5 to 10 per cent of 

 peanut oil can be detected by this method, as it effects a complete separation of the 

 soluble acids from the insoluble, which interfere with the crystallization of the 

 arachidic acid. Filter, wash the precipitate twice with 10 cc of 90 per cent (by 

 volume) alcohol, and then with alcohol of 70 per cent (by volume). Dissolve off 

 the filter with boiling absolute alcohol, evaporate to dryness in a weighed dish, dry 

 and weigh. Add to this weight 0.0025 gram for each 10 cc of 90 per cent alcohol 

 used in the crystallization and washing if done at 15 C. ; if done at 20, 0.0045 gram 

 for each 10 cc. The melting point of arachidic acid obtained in this way is between 

 71 and 72 C. Twenty times the weight of arachidic acid will give the approximate 

 amount of peanut oil present. No examination for adulterants in olive oil is complete 

 without making the test for peanut oil. 



