Other fixing agents
Other than the standard fixing agents discussed in other pages, there have been some used in the past which are now obsolete, or nearly so. There is no consistent reason for that, perhaps it was the cost, the corrosive nature of the chemical, ease of use and so on. Many of these still have their advocates, and they may very well perform admirably.
Copper salts are sometimes still spoken of as being very effective for nuclear preservation. The copper in fixatives which contain it may act as a mordant, in the true sense, for some dyes including hematein. This, of course, infers that copper is an additive fixing agent.
Platinum chloride was in use at the beginning of the 20th century, but its use never caught on since it is very expensive. The chemical actually used was chloroplatinic acid, which bears much the same relationship to platinum chloride as chloroauric acid does to gold chloride, that is, a convenient but inaccurate name.
In addition, some other heavy metals have been used on occasion, as have some aldehydes and alcohols. In many cases these chemicals have no particular advantage over those we usually employ, and may be more difficult to work with as being more expensive, toxic, inconvenient etc. Nevertheless, it can be interesting to investigate them for self-education. Should you do so, please use them and dispose of them safely.
You will find numerous examples listed in Gray.
Gray, Peter. (1954)
The Microtomist's Formulary and Guide.
Originally published by:– The Blakiston Co.
Republished by:– Robert E. Krieger Publishing Co.