Methyl violet indicator paper

The poiymer has a Qc of 3096cai/g (Ref liq H20 at 25°), an impact sensy of 85cm at the 50% point using a BM machine with a 2kg wt (RDX, 28cm), power by Bal Mortar of 96 (TNT=100), a thermal stability at 65.5° of 10 mins using a 1.3g sample with Kl-Starch paper as the indicator (Ref NC, 10 mins, no color), a thermal stability at 134.5° of 78 mins using Methyl violet indicator paper (Ref NC, 30 mins, no color), and a rel vise of 1.7 centipoises using a 1% acet soln at 25°... 

When phosgene is combined with A ,iV-dimethyianiiine in the presence of aluminium(III) chloride, Michler s ketone, 4,4 -bis(dimethylamino)benzophenone, is produced (see Section 10.2.1.1), which undergoes further reaction with lV,N-dimethylaniline (also in the presence of aluminium(ni) chloride or POCij) to give the colouring material "crystal violet", used in the production of methyl violet indicator paper. When Michler s ketone is warmed with Ai-phenyl-1-naphthylamine in the presence of POCI3, Victoria blue (4.13) is formed, which is used as a dye for natural fibres [718a]. 

Heat Tests. Heat tests are performed at 1 34.5°C for single-base propellants and 1 20°C for double-and triple-base propellants. These tests measure the stability of the propellant Specimens of the propellant are placed into the bottom five centimeters (two inches) of a glass test tube. A piece of methyl violet indicator paper is placed vertically in the tube so that the lower end of the paper is 25 millimeters from the specimen. The tube is corked and set into a constant temperature block or a constant temperature reflux bath. The temperature must be maintained to within 0.5°C. The result of the test is reported as the time required for the test paper to change color to salmon pink. For the propellant to pass the test, the color change cannot occur in less than 40 minutes or 60 minutes, depending on the propellant formulation, and the sample may not explode in less than five hours. 

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-... 

Add 1 drop of the methyl violet indicator solution and introduce dilute HC1 or dilute aqueous NH3 (as necessary) dropwise and with constant stirring until the colour of the solution is yellow-green a blue-green colour is almost but not quite acid enough, yet is acceptable for most analyses. (If the indicator paper is available, the thoroughly stirred solution should be spotted on fresh portions of the paper.) It is recommended that a comparison solution containing, say, 10 ml... 

In cases where a lot of proplnt has successfully passed the one-year exposure to methyl violet paper, only a 3% inspection of the exposed test strips need to be made thereafter until such inspection indicates progressive deterioration of the proplnt or other nonstandard condition, at which time 100% inspection and test of the lot under suspicion will be resumed It is considered desirable that succeeding annual inspections include at least 1/3 of the containers included in the original 3% inspection as outlined above. In this manner, such containers may be considered as a basic comparative control with reference to the balance of the lot under test... 

This applied particularly to double-base propints, although some single-base propints also gave erratic results. For these reasons, work was undertaken at Picatinny Arsenal to find an indicator that would be more reliable than methyl violet. About 60 commercially available dyes were examined by S. Helf (Ref 5) in exptl indicator paper tests, of which only three were found to be superior to methyl violet benzoazurine, trypan red and ethyl violet. Laboratory and surveillance testing showed that papers prepd with a 0.1% soln of benzoazurine did not change in color after one year when used with stable double-base propint, while methyl violet paper was bleached in nearly every case. The other two indicators mentioned above, trypan red and ethyl violet, were not as satisfactory as benzoazurine, although they were better than methyl violet. 

The polyester is stable in storage at RT. The thermal stability at 65.5° using a 1.3g sample and Kl-Starch indicator paper is failure after 100 mins (Ref NC, 10 min, no color) at 134,5 using a 2.5g sample and Methyl violet paper, failure is shown after SO mins (Ref NC, 30 mins, no color)... 

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,... 

O. 1% Ethyl Violet, 0.1% Trypan Red 0.1% Benzoazurine. On exposure to four different types of partially degraded but still serviceable double-base proplnts for a period of 1 yr, strips of each of these experimental indicator papers remained either unchanged or became only slightly faded. The N/10 Methyl Violet paper became, totally bleached within 3 months... 

Indicator papers frequently aid in the identification of chemicals. Strong mineral acids are acid towards methyl violet or thymol blue papers, moderately strong acids react acid towards Congo paper, and very weak acids are acid towards htmus and azolitmin paper. Strong bases show an alkaline reaction with turmeric or tropeolin 0 paper, medium strong bases with phenol-phthalein, and very weak bases with litmus or azolitmin paper. These papers are not recommended for use in quantitative analysis. ... 

Capillary phenomena may arise from other causes. Thus a solution of ammonium acetate turns both red and blue litmus papers violet. The drops are more bluish in the center and more red at the edge. It appears that the paper hinders the diffusion of ammonium hydroxide to a greater extent than it does the diffusion of acetic acid. The effect is even more evident when the reaction is produced with lead acetate. Around the center of the drop is found a blue region (adsorption of lead hydroxide) which is surrounded by a red region due to the diffusion of the acetic acid. These observations account for the discrepancy found in medical books regarding the reaction of lead acetate. It is impossible to determine accurately the reaction of this salt with litmus paper. It can be done, however, with methyl red solutions. The reaction resulting from the hydrolysis of salts such as sodium acetate and ammonium chloride is demonstrated readily by means of indicator papers. 

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. 

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