T H E J O URiVAL OF IlVD U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y .
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i t should continue to bear the burden of a raw material of a higher cost than that used b y its competitors, and returned t o the use of nitrocellulose. Trusting t h a t the above somewhat lengthy statement will make the situation plain t o your readers, we remain, Yours very truly, EASTMAN KODAKCOMPANY. ROCHESTER. N Y , September 26, 191 1
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NOTE ON THE DETERMINATION OF THE SPECIFIC GRAVITY OF ETHYL ETHER, U. S. P.
The following method for the determination of the specific gravity of ethyl ether has given sathfactory, practical laboratory results, varying not more than two points in the fourth decimal place. A calibrated pyknometer of 2 5 cc. capacity, as shown in the sketch, is employed. To determine its volume the pyknometer is first weighed with water a t 2 5 O C., choosing a convenient mark on the stem, say 30 or 40, whichever may be more convenient, as indicated in the sketch by a line. The pyknometer is then filled with ether t o a little above the mark
Nov., I 9 I I
A METHOD FOR FILTRATION.
Analysts, and particularly those who are engaged in organic work, are frequently confronted with solutions containing precipitates which require a long time t o filter and some indeed quite impossible. The following will serve to illustrate: Subacetate precipitate in vanilla extract, jams, various crude drugs, wines, etc., gelatinous starchy solutions, macerated tissues in toxicological work, ferric and aluminum hydrates, and in fact any precipitate likely t o clog the pores of filter paper, pulp or asbestos. The writer, after having tried many schemes without success, has a t last obtained most satisfactory results by means of a n apparatus consisting of a suction pump, and a heavy side-necked Erlenmeyer flask, in the stopper of which is inserted a Buchner filter of convenient size. Over the holes is placed a double filter paper; this is wetted to fit tightly over the holes and the paper is then sprinkled evenly with coarse, acid-wkhed and ignited sea sand to a depth of from I - I I / ~ cm. The filtration may then be begun. The same idea may be used for the preparation of Gooch' crucibles in weighing precipitates dried in the air bath. HALSEYDURAND. DEPARTMENT OF H E A L T H ,
NEW Y O R K
CITY.
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GENERAL NOTES.
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a t which the weight of water has been determined and placed in a I O Q O cc. beaker containing water which is carefully kept a t 2 5 O C. and constantly stirred with a thermometer. When the volume of ether becomes constant in the pyknometer the excess of ether is drawn off b y means of a capillary pipette until the desired mark is exactly reached. The pyknometer is then quickly dried with soft flannel or filter paper and weighed. A capillary pipette for this purpose is easily made b y drawing out a n ordinary eye-dropper. GEO. D. ROSENGARTEN. LABORATORY O F T H E POWERS-%'EIGHTMANROSENGARTEN Co , September. 1911
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Professor W. E. Adeney, F. I. C., curator and ex-Examiner in Chemistry of the Royal University of Dublin, arrived in New York City on October 7th, t o consult with the Metropolitan Sewerage Commission of New York on questions relating to the assimilation of sewage b y harbor waters. Dr. Adeney is distinguished for experimental researches in chemistry, the results of which have been published largely in the Transactions of the Royal Dublin Society and in the Proceedings of the Royal Irish Academy. With Professor Letts, of Belfast. he contributed a notable monograph on the pollution of estuaries and tidal waters with a description of experimental researches into the phenomena of the digestion of sewage by water, which was published as Appendix VI. of the Fifth Report of the Royal Commission on Sewage Disposal. A sulfuric acid plant with an annual capacity, of tons of acid is being erected in Cnrey, Ala., b y R. A. Brown &Company. zj,ooo
A committee dealing with the hygienic aspects of illumination has been appointed by the Minister of the Interior in France. The objects of the committee include the general effects of illumination on health, the framing of simple rules as to the best means of applying customary systems of lighting to various industrial operations, the nature and causes of short sight and impairment of vision, and their connection with defective living conditions, the study of methods of measuring illumination, etc.
