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and at t h e same time they can not readily become clogged with precipitate. This form has the advantage over t h a t in Fig. I t h a t t h e glass tubes are removable. If i t is desired t o eliminate t h e rubber stopper a t t h e base of t h e pipette, t h e construction of t h e lower end of t h e cylindrical bulb can be made identical with t h a t in Fig. I. An opening' (not shown in t h e figure) between t h e first and last two bulbs which is closed b y a small cork or rubber stopper is a great convenience in filling a n d cleaning t h e pipette. The specific absorption t h a t may be obtained in this pipette' is practically t h e same as t h a t obtainable with t h e pipette shown in Fig. I, aiz., 3 6 . I for t h e reagent prepared as suggested and exhausted under conditions t h a t are there specified. I t was found t h a t t h e pipettes t h a t have been described are not well adapted t o t h e analysis of samples of nearly pure oxygen12a n d for this reason no determinations of specific absorption for gas samples containing 90 per cent oxygen, such as have been published for t h e Hempel pipettes, were made. When a gas sample high in oxygen is placed in contact with t h e reagent in either of these pipettes in t h e usual manner, rapid absorption occurs up t o what apparently corresponds t o the exhaustion of t h e film of reagent upon t h e glass tubes and t h e inner wall of t h e pipette; thereafter absorption is slow unless t h e remaining gas is passed into t h e burette and returned in order t o moisten t h e contact material with fresh reagent. Even with this latter procedure, considerable time is consumed in effecting complete absorption, partly because of the intermittent contact of gas and reagent, and partly because of t h e decrease in t h e amount of contact material in proportion t o t h e size of t h e gas sample as the latter becomes small a n d occupies only t h e upper portion of t h e pipette above most of t h e glass tubes. Therefore, it is believed t h a t when t h e analysis of gases high in oxygen is frequently made, t h e Hempel pipette should be employed. On t h e other hand, when such samples are met with infrequently, as is usually t h e case, t h e longer time required for their analysis will not prove a great objection, especially if the pipette is shaken t o hasten t h e absorption when t h e volume of t h e sample has become too small t o uncover t h e tops of the glass tubes. SUMMARY
I-Pipettes especially adapted for use with alkaline pyrogallol are shown in Figs. I and IT. These pipettes are constructed in such fashion t h a t t h e formation of precipitate, a characteristic of alkaline pyrogallol of high specific absorption, is not objectionable until t h e reagent has nearly become exhausted. 11-It has been found possible t o employ a reagent containing a higher concentration of pyrogallol t h a n t h a t recommended for use in t h e Hempel pipettes. This reagent is prepared b y dissolving 2 j grams of pyro1 This construction is shown on a special pipette for use with cuprous chloride, designed by the United Gas Improvement Co., in the catalogs of Eimer & Amend and A. H. Thomas Co. 2 This appears to hold true for all pipettes in which the gas sample is not shaken with the reagent.
I35
gallol in I O O cc. of a solution of potassium hydroxide of I . j j specific gravity, which results in a volume of about 118 cc. There are thus 2 1 . z grams of pyrogallol a n d 6 6 . 6 grams of potassium hydroxide t o I O O cc. of t h e solution. 111-The specific absorption of t h e above reagent for I-minute contact is about 36 when treated in t h e proposed pipettes at room temperature (20'-24' C.) with gas samples I O O cc. in volume containing 2 0 . 9 per cent oxygen. This is a decided gain both in specific absorption a n d convenience of manipulation over t h e results t h a t have previously been obtained with t h e Hempel pipette (specific absorption z j , for I-minute shaking). No determinations of specific absorption for samples of nearly pure oxygen were made, since complete absorption can not be obtained in these pipettes in less t h a n 4 or 5 minutes unless shaking is employed t o facilitate t h e removal of last traces of oxygen. C O R L E L L U N I V E R S I T Y , ITHACA,
NEW
YORK
REAGENTS FOR USE IN GAS ANALYSIS IV-PHOSPHORUS IN SOLUTION By R. P. ANDERSONA N D W. BIEDERMAN
Received September 3, 1915
Centnerszwerl has proposed t h a t a solution of phosphorus be employed t o r.eplace solid phosphorus as a n absorbent for oxygen in gas-analytical work, since the behavior of t h e latter reagent is appreciably influenced by temperature, percentage of oxygen in t h e mixture, a n d t h e presence of certain other gases. Castor oil was chosen as t h e solvent for phosphorus because i t possesses a negligible vapor pressure a t ordinary temperatures and because i t dissolves t h e products of t h e oxidation of the solute. It was thought desirable t o study further t h e solution which Centnerszwer recommends, with t h e idea of determining how long a time is required for t h e complete absorption of oxygen under ordinary conditions a n d what specific absorption may thus be obtained. Accordingly, solutions of phosphorus in castor oil were prepared by t h e method which he employed, which is as follows: About 230 cc. of castor oil a n d 3 grams of well-dried phosphorus are placed in a flask of 2jo cc. capacity, a well-fitting stopper is loosely placed in t h e neck of the flask, and its contents heated in a n oil bath t o zoo'. The flask is then removed from t h e bath and dried with filter paper, and, after tighty inserting t h e stopper, i t is wrapped in a towel and vigorously shaken t o effect complete solution of t h e phosphorus. When cool, the solution is transferred t o a pipette and is then ready for use. T h e precaution of wrapping t h e hot flask with a towel before shaking, as specified by Centnerszwer, is a n important one as regards t h e safety of t h e operator, since considerable pressure is developed when t h e shaking is started, especially if t h e castor oil does not almost entirely fill t h e flask, and in one instance t h e flask was shattered by t h e pressure produced. Samples of air were brought into contact with t h e reagerit a t z j ' C. in Hempel pipettes for solid and liquid 1
Chem. Ztg.. 5 4 (1910). 494.
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reagents. I t was found t h a t t h e absorption of oxygen took place slowly a n d was in no case complete in a reasonable length of time. I n a typical experiment, t h e absorption a t t h e end of 3 minutes amounted to 8.4per cent, at t h e end of 6 minutes 14.8per cent, a n d at t h e end of g minutes 20.4 per cent. Incfeasing t h e time of contact of t h e gas and reagent did not result in any appreciable change‘in t h e volume of t h e sample. T h a t t h e absorption of oxygen was actually incomplete was shown by treatment of the residue with alkaline pyrogallol, whereupon a further decrease of 0.4 per cent was obtained, thus indicating approximately t h e correct percentage of oxygen in air. I t appears, therefore, t h a t t h e solution of phosphorus in castor oil is not suitabie for the gas-analytical determination of oxygen a t ordinary temperatures. No attempt was made t o maintain t h e reagent a t a n elevated temperature in order t o obtain complete absorption, since it is believed t h a t such a procedure mould complicate t h e determination of oxygen unnecessarily. Assuming t h a t complete absorption can be obtained with this reagent a t elevated temperatures, there seems t o be no reason why it should be preferred t o alkaline pyrogallol properly prepared.’ I n fact the latter reagent is much more convenient t o prepare, a n d by. its use practically complete absorption of oxygen can be obtained a t room temperatures in a much shorter time. CORNELL UNIVERSITY, ITHACA, ?SEW
YORK
THE UTILIZATION OF CULL FLORIDA CITRUS FRUITS2 By F . ALEX. MCDERMOTT Received November 3, 1915
I n t h e packing of citrus fruits, a considerable proportion of t h e fruit coming into t h e packing houses is unfit for shipment, a n d must be discarded; this discarded fruit constitutes t h e culls, and may amount, during poor seasons, t o as much as IO per cent of a given lot of fruit, though ordinarily the proportion is not so high. The usual causes of culling are extreme over- or under-size, stem-end rot, traumatic injuries t o t h e peel, and blue molds. A few of these culls are disposed of a t low prices for quick sales in the local markets, while a good proportion are consumed by t h e local cattle or simply allowed t o decay on t h e ground. A considerable number of these culls have t h e flavor a n d food value unimpaired, if utilized immediately. The main problems offered were ( a ) t o find a satisfactory process by which t h e juice of these culls could be preserved for at least two years, without conflict with t h e national or state pure food laws, a n d ( b ) t o develop a method by which t h e flavoring oil could be removed from the peels in such a manner t h a t t h e product would meet t h e commercial requirements for such a n oil, a n d could sell, THISJOURNAL, 7 (19151, 587 and 8 (1916). 131. 2Author’s abstract of a rather extensive report on the utilization of the cull citrus fruits from the packing houses in Florida, covering the author’s work on this subject during the period from October, 1911, to August, 1913, under the auspices of the Florida Citrus Exchange, at the Mellon Institute of Industrial Research, of the University of Pittsburgh. Publication has been withheld, up to this time, in accordance with the fellowship agreement; complete publication of the entire report will be made at a later date. 1
Vol. 8. S o .
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as a domestic product, in competition with the imported Italian oil. The recovery of t h e citric acid formed one of t h e minor problems. A large number of experiments were made with different processes t o determine their effect on the stability of t h e juice. As had already been observed, it was soon found t h a t simple pasteurization of t h e juice was not sufficient t o protect i t from further change; for a short time after pasteurization, usually less t h a n two weeks, t h e juice kept without apparent change, b u t after t h e lapse of this time a change of color became evident, t h e juice darkening and finally becoming muddy; this change in color *as accompanied by a deterioration in flavor, which eventually became offensively acrid. All specimens did not change t o t h e same degree, b u t it was found impossible t o correlate this difference between specimens with differences in acidity or sugar content. Such darkened specimens appeared t o be sterile, no organisms being shown by inoculations on standard agar or on sterilized orange juice, or under microscopic examination. The effect seemed t o be due to chemical action, but although a large number of tests were made, these failed t o indicate just what change had taken place in t h e darkened juice. I t was found, however, t h a t t h e removal of the air dissolved in the juice and t h a t in t h e container above it, followed by pasteurization, was sufficient to prevent this deterioration of t h e juice for a considerable time-in fact all failures which occurred within two years could be traced t o air having gained access t o the juice through leaks which developed in t h e stoppers on long standing under varying conditions of temperature. I t was found further t h a t , as would naturally be expected, it was t h e oxygen of t h e air which was active in producing this change, although replacing the air with pure oxygen did not produce as rapid and strong a darkening as would be expected, t h e effect being but little different from t h a t of air alone. It may be of interest t o note here t h a t t h e most common organized contamination of orange juice, which was encountered in this work, was a strain of the wild yeast (“Kahmhefe”) Willia anomala, and it is this organism which is responsible for the development of t h e ester odor (apparently ethyl acetate) which may so frequently be noticed in orange juice which has stood some hours a t room tem‘perature; t h e yeast was kindly identified for me by Dr. Alb. Klocker, of t h e Carlsberg Laboratory, Copenhagen. Acetic acid bacteria were also found occasionally, in every case observed being secondary t o t h e wild yeast, a n d on long standing various molds developed. The common blue molds of t h e peel of t h e orange, Penicillium italcum and P. olivaceum,appeared t o be unable t o grow on t h e sterilized juice, and all attempts t o inoculate them directly from infected fruit on this medium resulted instead in the growth of t h e Willie. The simplest method of effecting t h e removal of t h e air from and above t h e juice in t h e containers seemed t o be t o replace it by some non-oxidizing gas, and of those commercially possible, carbon dioxide appeared to be t h e best. A very large number of
