Test papers violet tests

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). 

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. 

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. 

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-... 

Seifert (Ref 1) modified the test by introducing a test paper (methyl violet or rosaniline) and observing the successive changes of color Refs 1) Seifert, Voyenske-Technicke pravy (Prague), 4, 42 (1927) 2) Reilly (1938) p 79... 

Indicator Test Paper for Detecting Stability of Double-Base Propellants. Approx 60 commercially available dyes were investigated in experimental indicator test papers. Laboratory surveillance tests indicated that 3 of these selected for further evaluation were less sensitive to double-base propint degredation products than N/10 Methyl Violet paper. The order of sensitivity was as follows N/10 Methyl Violet,... 

P. Rochlin, PATR 2242 (Sept 1952) (Concluded that the 3 experimental test papers appeared to be superior to N/10 Methyl Violet paper for detecting instability in stored proplnts)... 

It was adopted by the US Ordnance Dept (Ref 2), but the temperatures of the test were 120° for double-base propellants and 134.5° for single-base propellants for NC s (Ref 3). Litmus paper was originally used in this test (Refs 1 8c 2) but later this was changed id methyl violet paper and the test was called the Methyl Violet Test Apparatus ... 

Normal methyl violet test paper is prepd by soaking filter paper in a normal solution of rosaniline acetate-crystal violet and drying... 

The stability test for nitrocellulose powder at a temperature of 134.5°C the sample will not be considered serviceable unless the time necessary to produce the evolution of nitrogen oxides is at least 45 min and the powder withstands this temperature without exploding for 5 hr. The test can be combined with methyl violet test decoloration of the test paper should not occur before 30 min or longer according to particular specifications. 

The test for nitroglycerine powders at a temperature of 120°C (nitroglycerine powders cannot withstand higher temperatures) here the same conditions apply as in the test for nitrocellulose powders, viz. appearance of the nitrogen oxides after a lapse of at least 45 min and no explosion for 5 hr. The same test can be carried out in the presence of methyl violet test papers. Decoloration of the paper should not occur before 30 min. 

Sample Date of manufacture NaN02 in mg % Decoloration of methyl violet test paper at 120°C after min... 

Heat test at 134.5°C. This heat test is in use in the U.S.A. A sample of 2.5 g of nitrocellulose or nitrocellulose powder ( single base powder ) is kept in a long test tube in a constant temperature bath regulated to 134.5+0.5°C. A band of methyl violet (rosaniline acetate with crystal violet) test paper is kept over the surface of the sample. The test paper should not change to salmon colour before 30 min and no visible N02 vapours should be detected before 45 min. 

Test Papers. See under Methyl Violet Tests in Vol 8, M118-Lto M120-L, and Lead Acetate in Vol 1, A28-R... 

Methods in which the escaping nitrous gases can be recognized visually or by noting the color change of a strip of dyed filter paper. The former methods include the qualitative tests at 132, 100, 75, and 65.5 °C (270, 212, 167, and 150 °F). These tests include the U.S. supervision test, the methyl violet test, the Abel test, and the Vieille test. 

Sodium lodoplodinate Paper. This test-paper changes from its original pink colour to violet by the action of dichloroethyl sulphide, the intensity of the violet varying with the concentration of dichloroethyl sulphide. The papers are prepared by immersing strips of filter paper in an aqueous 0 2% solution of sodium iodoplatinate just before use. To test for the presence of dichloroethyl sulphide, the treated paper is exposed in a damp condition to the gas to be examined. Sensitivity 0 02 mgm. (Spica). 

Bra2il-wood Test Paper. Made by preparing the paper with a decoctloo of Brazil-wood. Alkalies turn it p orple or violet strong acids, red. 

Dfiuilia Test Paper. Mode from an infusion of the petals of the violet dahlia (georgiua purpurea) alkalies turn it green acids, red strong caustic alkalies turn it yellow. This is a very delicate test paper. The juice of elderberries will make a similar test uaper. 

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