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mination of the atomic weight ratio between bromine and hydrogen. This research forms a logical extension of that already done at the bureau by Drs. W. A. Noyes and H. C. P. Weber on the ratio between chlorine and hydrogen, a work that was crowned some time ago by the award of the Nichols medal. The force of chemists now employed numbered 13 on June 3oth, which number will be increased from 4 to 6 this summer, and probably by a number of others. A t present the quarters are uncomfortably crowded, but before the summer is over additional room will be provided to accommodate 17 or 18in all. There is a weekly journal meeting for the chemists, also certain courses of lectures and laboratory work to aid those who desire to take advanced university degrees. This latter work is done out of office hours and is accepted by some universities. In the foregoing I have endeavored to outline in the briefest possible manner the character of the chemical work done at the bureau. You will see that it is most varied and that administration and correspondence must necessarily make such large demands on my own time as to leave little for direct experimentation. The most that I can hope to do must be a t odd moments, but i t is my hppe and wish to be able to exercise direct supervision over the more exact analytical work, so far as this falls in line with my personal acquaintance. The bureau will, before long I hope, do its full share in the way of publication to forward the science of chemistry both practically and theoretically. But the bureau is yet young and so are most of its chemists. Hence actiye publication from the start is not to be expected, for unusual care must be taken lest work of doubtful value shall emanate from an institution which should be what its name implies, a Bureau of Standards. I t is too much to hope that this will never happen, but my aim will be to keep it at a minimum.
NOTES AND CORRESPONDENCE.. NOTE ON T H E VOLATILITY OF COCAIN. When cocain residues .?ere dried in a covered dish heated over the steam bath or at 100’ C. in a drying oven, i t was noted that a solid film soon collected on the cover. This sublimate was frost-like in appearance, insoluble in water, and on further examination was found to consist of cocain. The fact that this body is volatile a t 100’is importan; in connection with analytical work, if the analyst expects to heat a residue after the solvent has been evaporated, and a caution to this effect would not be out of place in the pharmacopeia1 directions for assaying coca leavs. Two cocain residues were tested by heating firsr for seven hours over a steam bath and then for seven hours in an oven a t 100’C., the weights being 0.0131gram and 0.0121 gram, the dish in the case of the first sample being open to the air and the second covered with a watch glass. A t the end of the first stage of the experiment they weighed respectively 0.0108 gram and 0.0104gram and at the end of the second stage 0.0083 gram and 0.0089 gram. There seemed to be practically no difference in the proportional loss whether the dish were covered or not. A cocain residue heated several hours in a drying oven at temperatures of 60°, 80’ and 90° suffered no loss in weight, and when heated to 98’ there was only a slight loss though there was considerable sublimation upward on the walls of the dish. I t was evident from the observations that the last portions of the solvent should be evaporated as rapidly as possible from a cocain residue, using a blast; and that the residual material should be dried cautiously, not over 90° and for safety should be brought to a constant weight by drying over sulphkric acid. H. C. FULLER.
Oct., 1910
NOTE ON DR. BACKE’S INVESTIGATION OF MALTOL AND ISOM ALTOL. Edztor Journal of Industrial and Engineering Chemistry: Since the, publication of my short paper on “ A Source of Error in the Examination of Foods for Salicylic Acid,” which was sent you September, 1909,and appeared in this Journal for January, 1910,i t has come to my notice that a communication relating to the same source of error was published by Dr. Arnold Backe in Annales des falsifications for November, 1909,and Dr. Backe has recently informed me by letter that the experiments upon which his communication was based were made in July of last year. Since my own experiments were made the month following, I beg space to acknowledge the priority of Dr. Backe’s work on this point over my own, and also to call attention to his more recent papers,’ in which he discusses the isolation and properties of the substances to which the interfering reaction is H. C. SHERMAN. due. ACCURACY IN SAMPLING. EdLtor Jourital 01 Industrial and Engineering Chemistry: On the appearance of hlr. Bailey’s paper on “Accuracy in Sampling Coal”* I gave it considerable study. By the time I had arrived a t my conclusions in regard to it, interest, judging by cessation of correspondence, had waned. I therefore hesitated to publish my views. The recrudescence of Mr. Bailey’s ,~ seems to warrant paper in that of Mr. F. B. P ~ r t e r however, calling attention to some errors in the former. Mr. Bailey began his paper by comparing some results obtained in the A. D. Little Laboratory with the results tabulated on pp. 281284, Professional Paper No. 48, U. S Geological Survey. This tabulation led Mr. Bailey into a n error which may best be explained by a concrete instance. 4833 Rs. of an Iowa coal were sampled and analyzed. This lot showed 20.70 per cent. ash, 10986 Rs. from the same carload showed 16.04per cent. ash, 12000 Rs. showed an ash of 14.46per cent. Of course, the proper way to obtain an average analysis is to multiply each analysis by the weight of the coal which i t represents, add the products and divide by the total weight of coal. Calculated in this manner the coal in question showed 16.17per cent. ash. The carload from which these portions were taken was sampled as a whole and showed 15.22 per cent. ash. The best value available for this coal is an average of the tw figures, 15.69per cent., and the error due to sampling is 0.47 per cent. In the averaging of the Geological Survey the figures were averaged, as much weight being allowed to the analysis representing 4833 Bs. as to the analysis representing the carload. Calculated in this way the average was 16.60 per cent., and the difference between that figure and 20.70 per cent., or 4.10per cent., Mr. Bailey considered error. Recalculating this tabulation the maximum error is 1.16per cent. and only 5 analyses out of 34 show an error greater than 0.7 per cent. It is probable that these higher errors would disappear if we could trace all the coal involved, but as it stands the maximum error is much less than that of the commercial laboratory as might reasonably be expected from the favorable conditions under which the government chemists worked. Whereas Mr. Bailey thought the government error was more than twice as large as the other. Mr. Bailey closes his comparison of these two sets of figures with the following statement: “As this data follows the probability curve very closely, the formula for probable and possible error can be safely applied in determining the reliability of different methods of sampling.” Even if Mr. Bailey had substantiated his formulae by correct figures there would be good reason to be suspicious of them on a Comfit. rend.. 150,540 and 151, 78. (1909). 3 Ibzd I, 148 (1910). 1
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