Paper tests

It is advisable to test the potassium iodide - starch pap>er with acidified sodium nitrite solution the commercial test paper is, particularly if it has been kept for a considerable period, sometimes almost useless. The solution must contain an excess of acid at all times, i.e., it must give a blue colour on Congo rod paper. 

This solution may also be employed in the test for bromine. If iodine has been found, add small amounts of sodium nitrite solution, warm shghtly and shake with fresh 1 ml. portions of carbon tetrachloride until the last extract is colourless boil the acid solution until no more nitrous fumes are evolved and cool. If iodine is absent, use 1 ml. of the fusion solution which has been strongly acidified with glacial acetic acid. Add a small amount of lead dioxide, place a strip of fluorescein paper across the mouth of the tube, and warm the solution. If bromine is present, it will colour the test paper rose-pink (eosin). 

Fluorescein test paper Is prepared by dipping filter paper into a dilute solution of fluorescein in ethyl alcohol it dries rapidly and is then ready for use. The test paper lias a lemon yellow colour. 

Plane one drop of the solution upon zireonium-alizarin-S test paper. A yellow eolour on the red paper indicates the presenee of fluoride. 

Stability. Heat stabihty is determined by measuring the time required for a specific amount of CN, held at 134.5°C, to decompose and discolor methyl violet test paper (75). 

The addition rate of the hydrogen peroxide must be adjusted so that the temperature of the reaction mixture does not rise above 10 C. The yield is reduced if the temperature is allowed to rise above that point. The end point of the reaction, when excess peroxide is present, can be determined with potassium iodide - starch test paper. The yield also is reduced if more than a slight excess of hydrogen peroxide is used. 

Ozon-isierung, /. ozonization, -messer, m. ozonometer, -messimg,/. ozonometry, -papier, -reagenspapier, n, ozone paper, ozone test paper. 

Papier-fabrik, /. paper factory, paper mill, -fabrikant, m. paper maker, -fabrikation, /. paper making, -farbe, /. paper color, -filter, n. paper filter, -flftche, /. paper sur-faee, surfaee of the paper, -gam, n. paper yarn, paper twine, -handel, m. paper trade stationery, -handlung, /. stationer s shop, -holz, n. pulpwood. -jod, n. a solution of iodine and potassium iodide for test paper, papierkaschiert, a. paper-covered, paper-baeked (as metal foil). 

Reaktions-losigkeit,/. absence of reaction, nonreaction. -masse, /. reaction mass, mass resulting from a reaction, -mischung, /. reaction mixture, -mittel, n. reagent, -ord-nung, /. order of a reaction, -ort, m. field or sphere of reaction, -papier, n. test paper, -rohr, n., -rohre,/. reaction tube, -stufe,/. step or stage of a reaction, -teilnehmer, m. participant in a reaction, reactant. 

The paper. strips used in the colorimetric method are impregnated with such dyes that the color of the test paper is dependent upon the pH of the medium in which the paper is placed. A standard color chart is supplied for comparison with the test strip. Test papers are available in a wide range type, which permits estimating pH to 0.5 units, and in narrow range papers, with which the pH can be estimated to 0.2 units. 

Another recipe for a universal indicator is as follows 0.05 g of methyl orange, 0.15 g of methyl red, 0.3 g of bromothymol blue, and 0.35 g of phenolphthalein in 1 L of 66 per cent ethanol. The colour changes are pH up to 3, red pH 4, orange-red pH 5, orange pH 6, yellow pH 7, yellowish-green pH 8, greenish-blue pH 9, blue pH 10, violet pH 11, reddish-violet. Several universal indicators are available commercially as solutions and as test papers. 

A. Adjustment of pH. For many EDTA titrations the pH of the solution is extremely critical often limits of + 1 unit of pH, and frequently limits of +0.5 unit of pH must be achieved for a successful titration to be carried out. To achieve such narrow limits of control it is necessary to make use of a pH meter while adjusting the pH value of the solution, and even for those cases where the latitude is such that a pH test-paper can be used to control the adjustment of pH, only a paper of the narrow range variety should be used. 

Into a conical flask, pipette a 50.0 or 100.0 mL aliquot of the solution and adjust the pH to 1-2 with aqueous ammonia solution (use pH test-paper). Add five drops of xylenol orange indicator and titrate with additional 0.05 M EDTA until the colour changes sharply from red to yellow. This gives the bismuth content. Record the total (combined) volume of EDTA solution used. Now add small amounts of hexamine (ca 5g) until an intense red-violet coloration persists, and titrate with the standard EDTA to a yellow end point the further consumption of EDTA corresponds to the lead-plus-cadmium content. 

Procedure. Prepare four test solutions of phenol by placing 200 mL of boiled and cooled distilled water in each of four stoppered, 500 mL bottles, and adding to each 5g of sodium chloride this assists the extraction procedure by salting out the phenol. Add respectively 5.0, 10.0, 15.0 and 20.0 mL of the standard phenol solution to the four bottles, then adjust the pH of each solution to about 5 by the careful addition of 5M hydrochloric acid (use a test-paper). Add distilled... 

An excess of sodium carbonate promotes foaming during the distillation, and is to be avoided. Since the neutral point is not easily recognized with test paper, the carbonate is added in decreasing amounts, until, a fresh portion is no longer decomposed with gas evolution. 

Note The Observation Test was intended to detect the initial decompn of propint, and was conducted at ail depots and posts where powder was stored. A 6oz sample of each lot of powder with a strip of methyl violet test paper was placed in a glass-stoppered bottle, with the paper not in contact with the powder. The test was conducted in the magazine in which the proplnt under test was stored. Bleaching of the test paper was taken as an indication that the powder had started to de-... 

Where definite loss of color by bleaching is noted, the content and container should be inspected to determine the cause. If correctable, such as a faulty gasket, broken container, etc, the gasket is changed or the powder is transferred to another container. A new strip of test paper is inserted and the proplnt replaced in storage with the container definitely marked to insure reinspection at the end of one year. 

As of this date the use of the new test papers has not been standardized... 

Development of an Indicator Test Paper for Detecting Stability of Double-Base Propellants , PATR 1782 (1950)... 

Reduction to S(IV) is the basis of two spot tests of Feigl, although these apply to other S(VI) classes, e.g. sulphonamides. Thus Feigl and Lenzer fused the sample with alkali to yield sulphite, then treating with hydrochloric acid and warming to expel sulphur dioxide they detected the latter with nickel(II) hydroxide on test paper, which yielded ultimately the black Ni(IV) oxyhydrate (see also Section C). In the other test FeigF fused the sample with sodium formate/alkali, cooled and acidified with sulphuric acid to liberate sulphur dioxide in this case also. This was detected by a ferric chloride/potassium ferricyanide reagent which yielded a blue colour (Prussian, Turnbull s). 

DEAL ion exchanger, Celluloflne A-200 (Wako Pure Chemical Industries, Ltd) Eilter paper, 11-cm i.d. pH test paper... 

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