Filters liquid

Preparation of benzyl cyanide. Place 100 g. of powdered, technical sodium cyanide (97-98 per cent. NaCN) (CAUTION) and 90 ml. of water in a 1 litre round-bottomed flask provided with a reflux condenser. Warm on a water bath until the sodium cyanide dissolves. Add, by means of a separatory funnel fitted into the top of the condenser with a grooved cork, a solution of 200 g. (181-5 ml.) of benzyl chloride (Section IV.22) in 200 g. of rectified spirit during 30-45 minutes. Heat the mixture in a water bath for 4 hours, cool, and filter off the precipitated sodium chloride with suction wash with a little alcohol. Distil off as much as possible of the alcohol on a water bath (wrap the flask in a cloth) (Fig. II, 13, 3). Cool the residual liquid, filter if necessary, and separate the layer of crude benzyl cyanide. (Sometimes it is advantageous to extract the nitrile with ether or benzene.) Dry over a little anhydrous magnesium sulphate, and distil under diminished pressure from a Claisen flask, preferably with a fractionating side arm (Figs. II, 24, 2-5). Collect the benzyl cyanide at 102-103°/10 mm. The yield is 160 g. 

Methyl y-bromocrotonate. Mix 36 g. of iV-bromosuccinimide, 40 g. of methyl crotonate and 60 ml. of dry, redistilled carbon tetrachloride in a 500 ml. round bottomed flask. Reflux ou a water bath for 12 hours by this time all the sohd should have risen to the surface of the liquid. Filter off the succinimide at the pump and wash it with a little dry carbon tetrachloride. Remove the solvent on a water bath and distil the residue under reduced pressure, preferably from a Widmer flask (compare Figs. II, 24, 4-5). Collect the methyl y-bromocrotonate at 77-78°/8 mm. the yield is 31 g. 

The liquid is filtered, and on extraction with ether yields some pipe-ronal (heliotropin), melting at 37°. The residual liquid is boiled with magnesium carbonate-, resinous matter extracted with ether, the liquid filtered and the acid set free by means of dilute sulphuric acid. Homopiperonylic acid crystallises out on evaporation, and forms fine needles melting at 127° to 128°. 

From the dropping funnel is next slowly introduced, with stirring, 40 g. (0.5 mole) of dry pyridine (Note 4) in 100 cc. of dry toluene. The ether is then distilled (Note 5) and the residual suspension stirred at no0 (inside temperature) for eight hours. It is then cooled to about 40°, 35 cc. of water cautiously added, and the liquids filtered if necessary (Note 6). The lower layer is separated and discarded. The toluene layer is dried for an hour with 20 g. of pulverized potassium hydroxide, and carefully distilled, using a fractionating flask (Org. Syn. Coll. 

Magnetic filters have been used to clean paint slips and liquids. Filters that are open to the atmosphere or closed, ie, pressure type, are available where the filter inlets are matched to standard pipe connections from 10 to 50 mm, for low capacity applications. 

Paint including paint, lacquer, enamel, stain, shellac solutions, varnish, polish, liquid filter, and liquid lacquer base 1263... 

To separate solids from a liquid, filtering through paper filters (smooth or fluted) is employed. Cotton wool, asbestos fibres, glass wool, crushed coal, porous glass, and a number of other materials can also be used as filters. The liquid separated in filtration is called the filtrate. 

The fixed residue supposed to contain barytic, sul-phato, -white lead, and chalk, may now be treated with pure and dilute nitric acid any insoluble matter.still remaining is set aside for examination, and the solution in nitric acid, which, if it was attended with, effervescence, showed the presence of carbonic acid, may be, if necessary, diluted with watsr,- Solution of sulphids of hydrogen gas is then added, and a black precipitata obtained, if lead be present. The clear, liquid filtered from the plumbic sulphide is next neutralized by ammonia, and osalats of ammonia added. A whits precipitate proves the presence of lime. 

Alkalies. — The solution of 2 gm. of ammonium phosphate in 100 cc. of water is treated with lead acetate solution in slight excess to precipitate the phosphoric acid, and is then filtered. The excess of lead in the filtrate is then precipitated with hydrogen sulphide, the liquid filtered, the filtrate evaporated to dryness, and the residue ignited. The residue should not be soluble in water, nor should it have an alkaline reaction. 

XI. Treatment by Meyer-Drutel Method. Prepare 15ml of satd aq soln of the sample, filter the soln and transfer 10ml of the filtrate to a test tube. Add 2ml of glac AcOH 0.2g Zn dust, shake the mixt, allow to stand 15 mins and note the color of liquid. Filter and add to the filtrate 2 drops of 0.1% K2Cr20 w/o shaking. A pale pink color which turns, on addn of K2Cr207,... 

Filtration of Hot Solution (see also Filtration).—This operation is usually necessary in order to remove insoluble impurities, filter fibres, etc. When the substance does not separate rapidly from the hot solution, and the liquid filters quickly, the solution may be filtered through an ordinary funnel with a short stem, fitted with a folded filter paper (Pig. 1). Both funnel and paper should previously be warmed in a steam bath. Or, the solution may be filtered with suction, using suitable types of apparatus (Pigs. 27,28). The funnel and filtering medium should be previously warmed. When the filtrate is collected in a thick glass suction flask,... 

The rubber is incinerated, the ash treated with a small quantity of nitric acid and boiling water, the liquid filtered and the filtrate analysed by the usual methods. 

GelatiAe.—5 grams of the powdered chocolate are treated with 50 c.c. of boiling water, 5 c.c. of 10% lead acetate solution being then added and the liquid filtered. The filtrate is tested with a few drops of saturated aqueous picric acid solution in presence of gelatine, a yellow precipitate forms. 

Procedure. 50 c.c. of the wine are evaporated in a platinum dish with about 1 gram of a mixture of nitre (1 part) and sodium carbonate (3 parts). The residue is charred, the carbonaceous matter washed with dilute nitric acid, the acid liquid filtered into a beaker, the residue washed with water and filter and residue thoroughly dried in an air-bath and incinerated in the original dish. The ash is moistened with nitric acid and taken up in boiling water, the solution being filtered into the beaker in which the first acid filtrate was collected and the filter and dish washed several times with hot water. 

The remainder of the sweet residue is treated with a few c.c. of a dilute sodium carbonate solution and the liquid filtered into a platinum dish and... 

Another is acidified with dilute hydrochloric add and treated with barium chloride for the detection of sulphate. Barium chloride is added until no further precipitate, forms and the liquid filtered, the filtrate being neutralised with soda or potash and again filtered the filtrate is treated with acetic add and calcium chloride if a white precipitate forms, this is separated and identified as calcium oxalate. 

Glycerine,—The ink is evaporated to a syrup, which is taken up in 96% alcohol and the liquid filtered the alcoholic solution is evaporated and the residue tested for glycerine as follows A few drops are heated in a test-tube with a crystal of potassium bisulphate. In presence of glycerine, the irritating odour of acrolein is observed and a spot of sodium nitro-... 

It is rarely necessary to determine quantitatively the separate components of the residue. When the lead sulphate is to be determined, the residue is extracted with ammonium acetate solution in the hot, the liquid filtered and the filtrate precipitated with hydrogen sulphide the lead sulphide is dissolved in nitric acid, and the procedure indicated in the next section (6) followed. 

Extraneous Organic Substances.—To detect glycerine and dextrin, the substance is mixed with water, the insoluble matter allowed to settle, the liquid filtered, the filtrate evaporated and the residue examined as to its external characters, polarisation, behaviour when heated, etc. Starch is detected microscopically, and fatty oils by extracting the substance with ether and examining the ethereal extract. 

Further, an aqueous solution of the colouring matter may be treated with basic lead acetate (a basic colouring matter should first be precipitated with tannin), the excess of lead eliminated, the liquid filtered and the sugars tested for or determined saccharimetrically or with Fehling s solution. 

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