ANALYTICAL EDITIOM
404
Vol. 2, x o , 4
Apparatus for Percolation at a Uniform Rate and Automatic Collecting Device' P. L. Hibbard COLLEGE OF AGRICULTURE, UNIVERSITY OF CALIFORNIA, BERKELEY, CALIF.
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HE apparatus t o be described was designed to permit percolation of a small amount of soil (20 grams) with a watery solvent at a uniform rate of flow continued for 15 to 30 hours, without attention after it is set in operation. After the first receiver of the percolate is filled, the flow is automatically shifted t o the next receiver till a whole series has
cessively filled. When the first one is filled, the flow is automatically changed to the next in the series. Percolation Apparatus
The whole apparatus is represented in Figure 1. The reservoir, A , consists of one or more 20-liter bottles, provided been fded without any personal attention. with siphons for withdrawing the solution and air-inlet tube The reason for making this somewhat complicated regulat- to control the flow on the principle of the Mariotte bottle. ing device is that it was not found possible t o secure a constant The siphon allows liquid to flow into the first jar, B , of the flow a t a uniform rate by any simpler contrivance, which regulating train, till it rises and closes the end of the air-inlet would continue to flow indefinitely a t a slow enough rate. tubes. To operate successfully the lower 30 em. of this air Stopcocks partly closed, pinch clamps on rubber tubing, capil- inlet tube should have an inside diameter of 8 to 10 mm.; lary tubes, ordinary siphons of small diameter-all failed above this it may be much smaller, 5 mm. The rubber when made to run slowly enough for the purpose in question. stoppers in the reservoir A must be tight enough so that no Since the apparatus here described was put in use, a siphon air can enter except through the single air-inlet tube. The on a float has been described by Sullivan (1). The writer liquid from the first jar of the regulating train flows through a siphon of small diameter into the second jar, then through another siphon into the third jar, D. From this jar another siphon, E , delivers the liquid to the first intermittent siphon A holder, 0. The purpose of the three jars connected by siphons is to maintain a n almost constant level of the liquid in the last jar, D , so that the siphon running from this will deliver the liquid a t a nearly uniform rate, which is about 40 drops per minute. The level of the liquid in jar B rises 2 to 3 em. a t the time the air-inlet tube admits air to the reservoir; therefore. jar C between B and D is used to equalize the flow, so that there is only a small corresponding rise in the level of the liquid in jar D. The delivery siphon, E, from this jar is held in a fixed position by a buret clamp, so that the outlet end of the siphon is 2 to 3 mm. below the level of the liquid in the jar. By turning the wing nut on the buret clamp screw, it is easy to adjust the height of the outlet siphon very exactly in order to regulate the flow. The outlet of this siphon must be about 5 mm. below the end of the tube which admits air to the reservoir in order to maintain a slow, even rate of flow. The liquid drops from the outlet siphon a t the rate of 40 to 50 drops per minute. If adjusted to run much slower than this, it is likely to cease flowing after a time. This rate is twice as fast as the flow desired for the percolator, so it is divided between two percolators by a distributor, J. First it collects in a receiver, G, of about 100 cc. capacity until the liquid is high enough t o overflow through the intermittent siphon in the bottom of the receiver. The internal diameter of this siphon is 4 to 5 mm., so that it requires several seconds to empty the receiver. The liquid drops from this siphon into another similar receiver, H , having a siphon 7 to 9 mm. 0 0 in diameter, which empties the receiver in a few seconds. This is done in order that the liquid may be delivered to the Figure 1-Percolation and Collecting Apparatus distributor so rapidly that the two outlets from the distributor will each deliver the same amount of liquid to the percolators. was unable to make this device operate successfully over any This makes it possible to run two or more percolators from the considerable number of hours. It would work for awhile, same distributor with almost exactly the same rate of flow then cease flowing, or sometimes a slight change in condition to each. The bottom of the distributor is closed by a rubber would considerably increase the rate of flow. stopper, through which pass three bent glzss tubes, all of the The present system consists of three main parts-a reser- same diameter, about 2 mm. inside. These tubes end just voir for holding the supply of solvent with the controlling inside the distributor above the rubber stopper. By pushing device t o regulate the flow to any desired rate, the percolator them up or down a little, they can be adjusted to deliver t h e with equalizing tube, and the receiving train which permits same amount of liquid in the same length of time. Or&collecting the percolate in several separate containers, suc- narily the outlet of one is closed so that all the liquid coming to the distributor is divided between two percolators. 1 Received May 21, 1930.
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INDCSTRIAL Ah-D ENGINEERI.1'G CHEMISTRY
October 15, 1930
From the distributor the liquid passes to the percolator through a glass pressure-regulating tube, L, 9 mm. inside diameter and 1.6 meters long. This tube must be wide enough so that the air can escape at the top of the tube a t the same time the liquid runs down. The chief purpose of this wide tube is to regulate the pressure of the liquid in the percolator so that it will always pass through a t the same rate, whether the soil in the percolator is fine or coarse. If it is coarse, the liquid percolates through without much pressure. If it is fine, and difficult for the liquid to pass through. the liquid fills up in the pressure tube until the pressure is enough to cause it to pass through as fast as it comes from the distributor. If the percolator is clogged so that the liquid does not pass away through it, there is a side outlet near the top of the pressure tube through which the liquid runs to a waste collector, M. From this it is returned to the main reservoir to be used again. The percolator is a wide glass tube 48 mm. in diameter drawn out to 5 mm. diameter a t the bottom. I n the bottom is a porcelain filter plate on which rests a layer of paper pulp 4 to 8 mm. thick. On this is placed sand, then the material to be extracted, 20 grams of soil. When the soil is very fine it is mixed with an equal or greater bulk of clean acid-washed white sand in order to permit more easy percolation. By the aid of the sand and the pressure-regulating tube, above the percolator, the rate of flow through the material is made the same, regardless of the nature of the material. The pressure tube passes through a rubber stopper in the top of the percolator. Collecting System
The collecting system to receive the percolate consists of R series of wide-mouth liter bottles fitted with 2-hole rubber
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stoppers. I n one hole of each stopper is a glass tube about 6 mm. inside diameter, and 5 to 6 em. long, which serves as air outlet. I n the other hole is the vertical stein of a glass T-tube of 4 to 5 mm. inside diameter. The different bottles are connected into a train by short pieces of rubber tubing joining the T of each bottle to the next. The T of the first bottle is connected to the outlet tube of the percolator by a rubber tube. When the system is in operation, the liquid coming from the percolator passes into the first collecting bottle, through the downward limb of the T. When the bottle is full, the liquid passes on through the horizontal part of the T and drops into the next collecting bottle. Thus the whole train is filled without personal attention after it is once started. For the system to work well the top of each bottle in the train should be about 4 mm. higher than the preceding bottle. This causes each to be completely filled before the liquid passes to the next bottle, and prevents any siphoning from first to second, etc. It may be thought that there will be some mixing or diffusion of the liquid passing through the T-tubes with the contents of the filled bottles over which it passes. Something of this does happen, but the amount is unimportant. The rubber connector between the percolator and the first collecting bottle may be easily disconnected a t any time in order to catch some of the percolate for a test as to completeness of the extraction. When it is necessary to refill the reservoirs, A , pinch clamps, Ab, are closed, Aa is opened to a vacuum pump, and thus the liquid is drawn up into the reservoirs through tube, Ac, from a lower supply bottle. Literature Cited (1) Sullivan, IYD. E A G CHEM, Anal E d , 1 , 233 (1929).
Determination of Beryllium in Aluminum' H. V. Churchill, R. W. Bridges, and M . F. Lee ALUMIXUM RESEARCHLABORATORIES, NEW K E N S I N G T O V . P A .
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H E separation 01 ueryllium from aluminum has been of much interest, if we may judge from the amount of work which has been done on the problem. From 1798 to the present time investigators have given this separation considerable study, and the increasing interest in beryllium as a constituent of light alloys has created a demand for an analytical method which can be used to determine accurately a small amount of beryllium in an aluminum alloy. The combination Havens-8-hydroxyquinoline method described herein meets this demand. Previous Methods
There are many proposed methods in the literature with claims of clean-cut separations. Some are satisfactory if the ratio of aluminum t o beryllium is not too large. However, the accurate determination of 0.25 per cent beryllium in aluminum would be a very difficult task by any of these methods. An exhaustive study of various methods was made by Britton ( 2 ) who states that, of the many methods proposed, only four are capable of giving quantitative results. They are the decomposition by boiling sodium hydroxide solutions (3, 10, 12, 1 4 , and the methods of Parsons and Barnes (9), Wunder and Wenger ( I S ) , and Havens ( 5 ) . 1
Received June 6. 1930.
Efforts to apply these methods to the determination of beryllium in aluminum led to the conclusion that only the Havens method possessed reasonable possibilities of securing accurate results and t h a t these could be obtained only by repeated separations. Another method considered was that of Moser and Niessner (8) wherein aluminum is precipitated by a saturated ammonium acetate solution containing 3 per cent tannin, the beryllium remaining in the filtrate. This procedure was rejected because it could not be used in the scheme of analysis without an extra separation for iron. The use of 8-hydroxyquinoline described by Berg ( I ) , Hahn and Vieweg (4))and Robitsrhek (11), and applied to the separation of beryllium from aluminum by Kolthoff and Sandell (6) and Lundell and Knowles ( 7 ) , has been thoroughly investigated. It is the opinion of the authors that this method gives the most satisfactory separation of aluminum from beryllium. An objection is the large amount of expensive reagent required in making an analysis when the ratio of aluminum to beryllium is large. For example, in the determination of 0.1 per cent beryllium in aluminum it is necessary to take a &gram weight to secure enough beryllium for a satisfactory precipitation. The precipitation of aluminum in this case would require a quantity of 8-hydroxyquinoline which, a t current prices, would be prohibitive.
