ChemicalConversionAlmostMadeEasy.docVIP

Chemical Conversion Almost Made Easy by D. William Reichner This article is intended to be incomplete. The conversions included in the chart are those I have found to be the most common and most useful in my compounding of formulas. Additional entries could be made. I invite correspondence that could further extend the use-fulness of the chart. If there is a sufficient number of generally useable conversions received, another article summarizing these in chart form will be prepared. A word of CAUTION. Some conversions can be made without any difficulty or change in the chemical action of a solution - while others simply MUST NOT be made. There are many factors that must be considered. Some compounds are more soluble than chemically-similar alternates. Others are more toxic, less stable, more expensive, difficult to obtain, contain undesirable impurities in its commercial form if not specifically prepared for photographic purposes, etc. The chart entries have been limited to easy conversions. Those that are NOT recommended for ALL applications are indicated by an asterisk next to the Specified Ingredient. The others are recommended under MOST conditions. There are very special applications where normally useable substitutions must not be used. For example, in preparing dry-packaging of fixer, the crystal form of Sodium Thiosulfate must not be used in place of the anhydrous form. This particular restriction applies to similar forms of chemicals used in dry-packaging. Producing the necessary alkalinity for photographic solutions can be perplexing. It is possible to produce the required alkalinity in some solutions by the use of a small amount of a highly caustic compound like Sodium Hydroxide, or by the use of a large amount of a milder caustic compound like Sodium Carbonate or Kodalk or Sodium Phosphate, Tribasic, or others. Does it really matter what is used as long as the degree of alkalinity reached is the same? It DOES matter:?Photographically speaking there are