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T H E J O C 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
LABORATORY AND PLANT PROTEIN CHARTS B y ALEXANDERSILVERXAN Received February 26, 1915
Thousands of crude protein determinations have been made i n t h e writer's laboratory during the past four or five years, so it is natural t h a t every possible effort should have been made t o economize time. Assistants who cobperated with t h e wri.ter made suggestions from time t o time but the first charts were prepared by Mr. Frank D. Shumaker, who plotted the acid readings as ordinates. Subsequently, h l r . William G . Haynes revised the charts, using alkali values
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as ordinates a n d preparing curves for all moisture percentages encountered in t h e cattle feeds analyzed. Some twelve t o fifteen charts are in use b u t the writer has had only three of t h e curves plotted; these have been p u t on one sheet, owing t o the limitedspace here available. Of substances having a protein content up t o 20 per cent. a z g. sample is taken for analysis; for higher values, a I g . sample. T h e maximum encountered in feeds and raw materials used therein was about 4 3 per cent. Xmmonia is distilled over into 2 5 cc. N / 5 acid and
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t h e excess titrated with equivalent alkali. The alkali reading is then looked u p on t h e ordinate of the chart prepared for the feed of the particular moisture content found, a n d the crpde protein reading made on t h e abscissa. The charts are presented for the purpose of lightening t h e labors of other chemists doing similar work, a n d t o suggest this simple method for calculating results, as a n entire set of charts can be prepared in a very short time. DEPARTMENT OF CHEMISTRY, UNIVERSITY OF PITTSBURGH
GAS-WASHING APPARATUS WITH ENCLOSED FILTER’ By
E. R . WRAVERAND J. D . EDWARDS Received February 15, 1915
The three forms of gas-washing apparatus illustrated, although involving no new principles, are believed t o be somewhat novel in form a n d they have given such satisfactory service t h a t a description of t h e m may be of interest t o other chemists, especially as showing the arrangement of the parts for various uses.* Two of the forms permit a filter t o be placed within the apparatus b y means of which a precipitate may be separated a n d washed without exposure t o the air. This feature, in a simple a n d efficient gas wash bottle, is ,believed t o be new a n d has been found useful for various purposes. All of t h e forms illustrated possess the following advantages: I-They give thorough washing by keeping t h e gas in contact with t h e liquid for a long time and yet they
require b u t a comparatively small pressure for their operation. 2-They provide very efficient circulation of the absorbing liquid, which prevents the saturation of one portion of t h e liquid while another portion remains unsaturated. 3-They can be filled or emptied without disconnecting, and, indeed while in use if the tube for introducing t h e reagent is arranged as shown in Figs. I1 a n d 111. T h e apparatus illustrated in Fig. I is designed to Published b y permission of the Director, Bureau of Standards. * S e e also Cumming, Ckem. News, 101 (1910). 39; J. D. Edwards, THISJOURNAL,6 (1914). 468; Purves (Gray’s apparatus), Gas World, 60 (1914). 897. 1
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thoroughly wash a stream of gas with a minimum amount of liquid a n d with t h e lowest possible operating pressure. The series of bulbs blown along the top of t h e absorption tube aid the absorption by prolonging the time of contact between gas a n d reagent, but do not prevent t h e apparatus from draining completely. The construction is so simple t h a t t h e apparatus may be readily made up from glass tubing. Fig. I1 illustrates a simple washing apparatus designed for t h e precipitation a n d determination of acetylene or carbon dioxide, the precipitate being filtered off a n d washed without exposure t o the air. A Witt plate a n d asbestos filter a t t h e drain cock are covered with a layer of glass beads or another Witt plate t o prevent the filter being loosened by the circulation of the liquid. The beads near t h e outlet serve t o b r e a k u p the gas bubbles a n d prevent loss of liquid, as well as furnish additional surface. When t h e absorption is complete, the stopcock on the outlet is closed, t h e stopcock below t h e filter opened, a n d t h e filtration allowed t o proceed under the pressure of t h e inflowing gas; suction can be used if desired. Washing is accomplished b y introducing wash water through the funnel tube near t h e gas outlet, t h e liquid being forced through t h e filter by gas pressure as before. A straight absorption tube is used instead of t h e bulb tube shown in Fig. I because of t h e difficulty of washing a precipit a t e clinging t o t h e bulbs. A helical wash bottle, Fig. 111, is t h e same in principle a n d operation as No. I1 but has been designed with a view t o economy of space. This apparatus is very compact a n d efficient, giving as complete absorption as several ordinary wash bottles in series, while requiring only a small fraction of the pressure necessary t o operate the latter. With gas flowing a t t h e rate of I O O cc. per minute the bubbles remain in the helix about seven seconds. Bubbles passing a t t h e rate of one or two per second remain in the tube nearly t w e n t y seconds. Gas passed a t t h e rate of joo cc. per minute is still broken into fairly small bubbles a n d receives a very thorough washing, b u t if t h e gas is t o be passed a t a more rapid rate t h a n this t h e helix should be made of tubing of larger diameter. This form of apparatus is much easier t o make t h a n , a n d quite as efficient as some of the more elaborate apparatus on t h e market in which the gas bubbles follow a helical path. It possesses the additional advantage of permitting t h e filtration a n d washing of a precipitate within t h e apparatus without exposure t o t h e air. For satisfactory operation, it is necessary that the diameter of t h e absorption tube in all three forms be properly proportioned to the rate of gas passage. This tube should not be made too small. A tube
