ON THE COMPOSI!MON OF MILE AND BUTTER 245 ESTIMATION OF ACETONE IN PRESENCE OF ETHYL ALCOHOL. BY JITENDRANATH RAKSHIT. MESSINGER (Bey., 1888, 21, 3366) has described a titrimetric method of estimating acetone based upon its quantitative conversion into iodoform when acted on by caustic potash and iodine. Under these conditions some iodoform is formed from the ethyl alcohol, the amount of which depends on the temperature of the reaction.Although the substitution of ammonia for potash avoids the formation of iodoform from alcohol, its use is not practicable, owing to the decomposition of the iodides of246 ESTIMATION O F ACETONE I N PRESENCE OF ETHYL ALCOHOL nitrogen into nitrogen and hydriodic acid and the consequent loss of free iodine. It was found that if potash be replaced by baryta or lime water, the estimation can be successfully carried out under the following conditions : The sample to be examined, containing about 0.05 grm.of acetone, is placed in a 750 C.C. flask, and 300 C.C. freshly prepared lime-water added; the flask is loosely closed with a rubber cork, and heated to about 35" C. Drop by drop 5 C.C. of iodine solution are added and shaken for five minutes, then another 5 C.C.iodine solution is similarly added and shaken, and so on till 40 C.C. iodine solution are added. The gradual addition of iodine is necessary, because if all the iodine is added at once the reaction is not complete. If, during the addition of iodine, the colour persists after thorough shaking, more lime-water should be added.Ten minutes after the final addition of iodine a few drops of starch solution are added, the contents of the flask shaken and cooled, and 15 C.C. sulphuric acid added, and the excess of iodine titrated with & sodium thiosulphate. The number of C.C. of iodine used up, multiplied by 0.00193, is the quantity of acetone in the sample taken, The results of some typical experiments carried out by the method are tabulated below : Sample.0.020 grm. acetone ... ... ... 0.025 grm. acetone ... ... ... 0.045 grm. acetone ... ... ... 0.050 grm. acetone ... ... ... 10.050 grm. acetone + 1 C.C. methyl alcohol ... 0.050 grm. acetone + 0.125 C.C. ethyl alcohol 0.050 grm. acetone + 0.50 C.C. ethyl alcohol 0.050 grm. acetone + 0-75 C.C. ethyl alcohol 0050 grm. acetone + 1.0 C.C.ethyl alcohol ... 0.050 grm. acetone + 2.5 C.C. ethyl alcohol . . . #0*050 grm. acetone + 4 C.C. ethyl alcohol . . . 80.050 grm. acetone + 5 C.C. ethyl alcohol . . . ... ... ... ... ... ... ... ... ... ... ... ... I consumed. C.C. 10.2 12.8 23.3 25.7 25.7 25.9 26.1 26.4 26-5 27.6 28.9 29.8 Acetone found. Grin. 0.0197 @0247 0-0450 0.0496 0.0496 0.0500 0.0503 0.0509 0.0510 0.0532 0-0557 0.0575 I t is thus seen that the error due to ethyl alcohol is slight.A mean of fifty analyses showed that 0.8 C.C. of iodine is absorbed by 1 C.C. of ethyl alcohol, and if this correction be applied to the last four analyses, the amounts of acetone become 0,0496, 0.0494, 0.0496, and 0.0498 grm. respectively. When the sample contains only about 1 part of acetone and 100 parts of ethyl alcohol, the results are not so reliable, as the correction figure becomes too high in comparison with that for acetone itself, but samples containing 1 part of acetone with 10 parts of alcohol give accurate and concordant results. CEEYICAL LABORATORY, GHAZIPORE, IXDIA.