904
T H E JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
There is b u t little change in the specific gravity of t h e fruit held in storage during the first 60 t o 7 0 days, and even u p t o t h e end of t h e experiment t h e increase is slight a n d may be accounted for b y a normal drying-out or withering of t h e fruit. But with t h e fruit t h a t remained on t h e tree there is a t first a very marked decrease in specific gravity and t h e n apparently a gradual increase. It was noticed in cutting this orchard fruit t h a t during t h e latter half of t h e observation period t h e lemons appeared t o be filling out a little. S UJ?hf A R Y
I n so far as a preliminary experiment of this kind can be considered as giving definite results, t h e following conclusions may be drawn: I-The lemons t h a t remained on t h e trees after being frozen retained less juice and considerably less acid t h a n t h e fruit picked immediately after being frozen and stored a t a temperature of 45 t o 50' F. 11-The frozen fruit left on t h e trees decreased rapidly in specific gravity due t o t h e loss of juice a n d acid and t h e formation of thick, puffy skins, dried-up cells and hollow centers. 111-Lemons picked immediately after being frozen and stored under ordinary packing house conditions retained somewhat less juice t h a n the unfrozen fruit, b u t t h e composition of t h e juice was nearly the same, and in weight and appearance t h e slowly thawed lemons compared well with normal fruit. We wish t o acknowledge our indebtedness t o Mr. G. 'A7. Hosford of t h e San Dimas Lemon Association for his valuable suggestions and hearty cooperation, and t o t h e association for so generously supplying us with t h e fruit used in this investigation. BUREAUO F
CHEMISTRY, WASHINGTON
AN IMPROVED M E T H O D F O R THE DETECTION O F ARACHIDIC ACID By ROBERT H. KERR
Vol. 8, No.
IO
METHOD
Weigh out 20 g. of t h e oil t o be tested in a 300 cc. Erlenmeyer flask, pour in 2 0 0 cc. of 95 per cent ethyl alcohol, and heat t o boiling on t h e steam bath. When t h e alcohol is boiling add I O cc. of t h e potassium hydroxide solution. Saponification begins immediately and is soon complete. After t h e saponification has been completed add a few drops of phenolphthalein and neutralize t h e excess alkali with t h e alcoholic solution of acetic acid. Next add jo cc. of t h e 5 per cent magnesium acetate solution and heat t h e whole mixture t o boiling. Allow t o cool t o room temperature with occasional shaking and then place in a refrigerator a t a temperature of I O t o I j o C. and leave until next day. Filter off t h e solution, wash t h e precipitate twice with j o per cent alcohol a n d three times with distilled water, and return t o t h e flask in which precipitation took place. Pour I O O cc. of hot distilled mater into the flask and add sufficient dilute sulfuric acid t o decompose the magnesium salts. Heat until t h e separated acids form a clear layer. Cool t h e flask, pour off t h e acid solution, add I O O cc. of hot water. When the f a t t y acids have melted and solidified, pour off water as before. Free t h e cake of acids of water as far as possible b y draining; dissolve in I O O cc. of 90 per cent alcohol and separate t h e arachidic acid by crystallization, according t o t h e present provisional method of the Association of Official Agricultural Chemists as given in Bulletin 107, Revised, Bureau of Chemistry, p. 146. The method as outlined above has been used on a number of samples of peanut oil and mixtures of peanut and other vegetable oils. T h e results obtained are qualitative only, no attempt having been made t o apply t h e method for quantitative purposes. It has been found t o be capable of detecting j per cent of peanut oil in olive oil, cottonseed oil, soy bean oil and corn oil. These results are quite as good as t h e best which have ever been obtained with Renard's method. RCREAU O F ANIMAL ISDUSTRY,
WASHINGTON
Received May 16, 1916
T h e method described below for t h e detection of arachidic acid in peanut oil and mixtures of oils containing peanut oil has been found t o offer certain advantages over t h e Renard method adopted b y t h e Association of Official Agricultural Chemists. These advantages consist in greater convenience, lessening of t h e number of operations, reducing t h e amount of attention required, and avoidance of t h e use of ether. REAGENTS
Potassium Hydroxide Solutioiz-Dissolve I O O g. of stick potassium hydroxide in I O O cc. of water. Magnesium Acetate Solution-Dissolve I O g. of magnesium acetate in a mixture of I O O cc. distilled water and I O O cc. of 95 per cent alcohol. Acetic Acid Solution-Mix 50 cc. glacial acetic acid with 150 cc. of 95 per cent ethyl alcohol. jo cc. concentrated Suljuric Acid Solution-Mix sulfuric acid with 150 cc. of distilled water. 90 per cent E t h y l Alcohol (by volume).
THE HYDROLYSIS OF ETHYL-SULFURIC ACID AND THE ASSAY O F AROMATIC SULFURIC ACID, U. S. P. By W. B. D. P E N X I M A N ,W.W. RAKDALL, c.0. M I L L E R Received September 1, 1916
AND
1,. H. ENSLOW
Aromatic sulfuric acid is a mixture of sulfuric acid, ethyl-sulfuric acid, certain aromatics and alcohol. I t is prepared b y bringing together, according t o t h e U. S. Pharmacopoeia, 111 cc. of concentrated sulfuric acid and 7 0 0 cc. alcohol, and, after t h e mixture has cooled, adding jo cc. of tincture of ginger, I cc. of oil of cinnamon, and sufficient alcohol t o bring t h e total volume up t o one liter. The proportion of ethyl-sulfuric acid present depends upon the strength of t h e sulfuric acid and alcohol used and upon the length of time t h e mixture remains hot, and probably increases t h e longer the liquid stands, even when cold. The Pharmacopoeia (Eighth Revision) is not concerned with t h e ethyl-sulfuric acid: its only demand is t h a t t h e mixture shall contain not less t h a n 2 0
