262 T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y . Apr., 1 9 9

The reasons for employing these readings rather than any other physical constant, were ease of application and smallness of amount required, the time consumed being but a few moments, and a drop or two of material being amply sufficient for the determination.

The readings given in connection with the fractionation results are supplied merely to show the impracticability of arriving a t quantitative results by that method. Some other physical constant might have been used, and undoubtedly have answered equally as well.

The readings given in connection with the writer’s method -and I would emphasize that these are by no means aa essential part o i the method-are interesting merely as they demonstrate the possibility of recognizing, very quickly, approximately, the kind of petroleum products used, low readings indicating light products, high readings, heavier ones.

The writer took the readings a t z j o C., and used ordinary white light, those being the most convenient conditions ; and these having been used throughout, the figures given, are comparable with each other. It is assumed that each operator, before using this or any other similar new method, will try i t on known substances, and will use his own stand- ards and constants, as a basis for comparisons and con- clusions. ARTHUR E. PAUL.

LABORATORY OF MARINER AND HOSKINS. CHICAGO, ILL., Feb. 13. 1909.

DETERMINATION OF ACETANILID IN HYDROGEN PEROXIDE SOLUTIONS.

Recently I had occasion to determine the proportion of acetanilid in a commercial sample of hydrogen peroxide. Our client stated that one chemist whom he had consulted on the subject, declared i t to be impossible, and i t must be admitted, that so far as the literature is concerned, there seems to be nothing to fit that particular case.

It is a matter of record that boiling acetanilid with strong hydrochloric acid or with strong caustic alkali, causes a dissociation, with formation of anilin. The reaction is quantitative. The method of Seidell’ depends on this con- version by acid. A five minute vigorous boiling in a solution containing about one-fourth of concentrated hydrochloric acid was found by him sufficient to effect the change. That observation I have been able to confirm. I n the solution after cooling i t was found possible to determine the anilin by titration with Koppeschaar’s solution-practically the solutim used in urea determinations diluted to a convenient strength. The end reaction is when all of the anilin has been precipitated as the bromine substitution product, when the excess of bromine imparts a yellow tinge to the solution. For standardizing or for determining acetanilid in many pharmaceutical preparations, his process serves very well, but in the presence of the peroxide, the preliminary boiling completely destroys the acetanilid, affording a yellowish solution in which bromine gives no precipitate.

It was found that the desired result could be obtained by boiling with strong caustic alkali in presence of granulated

- zinc, and distilling over the anilin formed, by the aid of a current of steam. After some experimenting, the following plan was worked out: I n a side-neck flask of 200 cc. capacity, place about half a stick of caustic potash or soda (6-7 grams).

1 J. Am. Chem. Soc. , 29, 1091.

Add about 20 cc. of water to dissolve, and then 25-30 grams of granulated metallic zinc (the zinc had best be in as fine particles as can be obtained in “granulated” form. There is reason, however, to believe that “zinc dust” is too finely divided for this purpose). Then add a measured amount (not over 50 cc.) of the solution to be tested. Connect the flask on the one side with a flask to supply steam, arranging the tube to deliver steam near the bottom of the solution; connect on the other side with a condenser. The condenser should deliver into a Peligot bulb tube or some other arrange- ment by which the distillate is immediately brought in con- tact with moderately strong hydrochloric acid.

Raise the heat on the flask slowly, and when nearly hali‘ of the contents have distilled over, start the steam to passing through. The end of the distillation is a matter of guess. When the anilin is coming over in quantity, fumes are to be seen in the receiver, but for the last portions they cannot be seen. \\’hen i t is judged that all has come over, detach the receiver and catch what comes over later in a fresh receiver or a beaker, and titrate i t separately.

To prepare the volumetric bromine solution, dissolve 2 5 grams of caustic potash in 20-40 cc. of water, cool, and add liquid bromine until i t appears supersaturated. Then dilute to about zoo cc. and boil out excess of bromine (judged by the color). This should give a solution of which I cc. = nearly 0.01 gram acetanilid. Standardize by means of a solution containing 0.5 gram acetanilid in zoo cc. of water, using 30-50 cc. lots at a time, treated either by distillation on the manner above given, or by boiling with strong hydrochloric acid. Either method was found to give the same result with the same amount of acetanilid,

The method was tested by first distilling known quantities of the sample and titrating the distillate, then adding known amounts of acetanilid to the same quantities of the sample, and distilling. The distillates took just the additional amount required by the acetanilid added.

The presence of acetanilid was indicated by obtaining the iso-nitril reaction on the original sample.

Cool, and dilute to one liter.

ELWYN \TALLER.

NOTE ON MR. BAILEY’S PAPER ON ACCURACY IN SAMPLING COAL.‘

In the carefully planned and admirably carried out series of experiments described in his paper Mr. Bailey has shown that the errors due to sampling are likely to be much larger than most of us have realized. While the paper deals specifically with coal, the conclusions are applicable to the sampling of all mixtures of solids. It is the first attempt that has been made to measure quantitatively the errors due to too small a n initial sample and to insufficient crushing before quartering. No one realizes more fully than Mr. Bailey that there are other parts of sampling than those he has investigated, in which serious errors may occur. The U. S. Steel Corporation have studied some of these and formulated rules for taking samples of their principal raw materials.

This society and others have done much to insure the introduction of more accurate methods of analysis, bu t no one has done anything to insure that the samples represented the material correctly. To insist on the use of methods that

THIS JOURNAL, March, 1909.