Silver timing

It is clear that the freight value depends on the type and amount of film and how the production is spread over time. Figure 3 shows 2 simulations of silver concentration in fixer for different processing regimes. In one case, 10 m of film is processed over 3 hours. In another case, 10 m of film is processed over 16 hours. It is clear that the silver level in the fixer not only depends on the amount of film processed, but also on the distribution of the working load. The simulated daily freight values are 44 and 16 mgW respectively. ... 

Does not reduce ammoniacal silver nitrate or Fehling s solution. If, however, the sucrose solution is warmed for some time with the reagent in question, slight hydrolysis to glucose and fructose does take place and reduction then occurs occasionally samples of sucrose will rapidly give a silver mirror, presumably owing to impurities. 

I he methyl iodide is transferred quantitatively (by means of a stream of a carrier gas such as carbon dioxide) to an absorption vessel where it either reacts with alcoholic silver nitrate solution and is finally estimated gravimetrically as Agl, or it is absorbed in an acetic acid solution containing bromine. In the latter case, iodine monobromide is first formed, further oxidation yielding iodic acid, which on subsequent treatment with acid KI solution liberates iodine which is finally estimated with thiosulphate (c/. p. 501). The advantage of this latter method is that six times the original quantity of iodine is finally liberated. 

Add a known volume ofo oaM.AgNOj solution (in excess) and boil the solution until the silver chloride has coagulated. Filter through a conical 5 cm. funnel, ensuring that the filter-paper does not protrude above the r m of the funnel. Wash the silver chloride and the filter-paper several times with a fine jet of distilled water. To the united filtrate and washings add i ml. of saturated ferric alum solution. The solution should be almost colourless if it is more than faintly coloured, add a few drops of concentrated nitric acid. Then titrate with 0 02M-ammonium thiocyanate solution until the permanent colour of ferric thiocyanate is just perceptible. (Alternatively the chloride may be determined potentiometrically.)... 

Ammoniacal Silver Nitr. te. Add 1 drop of 10% aqueous NaOH solution to about 5 ml. of silver nitrate solution in a test-tube then add dilute NHg drop by drop with shaking until only a trace of undissolved Ag O remains. A number of reductions require the presence of Ag " ions. It is often advisable, therefore, after adding the ammonia to add silver nitrate solution until a faint but permanent precipitate is obtained. The solution should always be prepared in small quantities immediately before use, and any unexpended solution thrown away afterwards. If the solution is kept for some time, it may form explosive by-products. 

The method is generally applicable when other modes of esterification are either slow, inefficient, or likely to cause isomerisation it is, however, time-consuming and expensive. Small quantities of acid impurities are sometimes produced, hence it is advisable to wash the ester with saturated sodium bicarbonate solution. The silver salt can usually be prepared by dissolving the acid in the calculated quantity of standard ammonium hydroxide solution and... 

The conversion of a diazo ketone to an acid amide may be accomplished by treating a warm solution in dioxan with 10-28 per cent, aqueous ammonia solution containing a small amount of silver nitrate solution, after which the mixture is heated at 60°-70° for some time. Precautions should be taken (by use of a. safety glass shield) when heating mixtures containing ammoniacal silver nitrate. 

Prepare the silver oxide by adding a dilute solution of sodium hydroxide to 10 per cent, silver nitrate solution until precipitation is just complete, avoiding an excess of edkali. Wash the precipitate several times by decantation finally, Ster at the pump and wash well with water. 

Anglo-Saxon, Seolfor siolfur L. argentum) Silver has been known since ancient times. It is mentioned in Genesis. Slag dumps in Asia Minor and on islands in the Aegean Sea indicate that man learned to separate silver from lead as earl as 3000 B.C. 

Bronze disease necessitates immediate action to halt the process and remove the cause. For a long time, stabilization was sought by removal of the cuprous chloride by immersing the object in a solution of sodium sesquicarbonate. This process was, however, extremely time-consuming, frequentiy unsuccesshil, and often the cause of unpleasant discolorations of the patina. Objects affected by bronze disease are mostiy treated by immersion in, or surface appHcation of, 1 H-henzotriazole [95-14-7] C H N, a corrosion inhibitor for copper. A localized treatment is the excavation of cuprous chloride from the affected area until bare metal is obtained, followed by appHcation of moist, freshly precipitated silver oxide which serves to stabilize the chloride by formation of silver chloride. Subsequent storage in very dry conditions is generally recommended to prevent recurrence. 

There is a general relationship between metal price and terrestrial concentration. Metals present at relatively high concentrations, in the earth s cmst, such as iron and aluminum, are the least expensive rare metals such as gold and platinum are the most valuable. This situation has existed for gold and silver valuation for centuries. The amount of silver in the earth s cmst is approximately 20 times that of gold, and the historical price ratio for gold and silver varied between 10 and 16 for over 3000 years. Since 1970 that price ratio has been strongly affected by market forces and investor speculation. 

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