160 
(a) to \ gallon of 10% formalin 1 level teaspoonful of borax or 
(b) to 1 pint of concentrated formalin add 2 ounces of hexamine and 6 
pints of water or 
(c) to 1 pint of concentrated formalin add 5 pints of water and 3 
ounces of concentrated ammonia solution. 
If it is necessary to closely examine specimens from formalin, they may 
be deformalized by a few minutes immersion in a solution made by addition 
of 1,260 gm of NaHS0 3 and 840 gm of Na 2 S0 3 to 4.5 gallons of water. 
Paraformaldehyde 
The white powder paraformaldehyde is a polymer of formaldehyde. 
It can be converted to formalin. Because of its small bulk it is convenient 
to take on long expeditions or air trips, or as a source of emergency preserva- 
tive. To prepare 10 per cent formalin from paraformaldehyde, 16 grams of 
paraformaldehyde and 4 grams of anhydrous sodium carbonate are mixed. 
A small amount of wetting agent, such as Alconox, aids in dissolving these. 
It may be packed in vials or polyvinyl film (such as Saran-wrap or Parafilm) 
packs. Each packet mixed with 400 ml of cold water will produce a 10 
per cent buffered formalin solution (slightly alkaline but good for temporary 
field storage). When mixed with hard water, a slight but harmless pre- 
cipitate of calcium carbonate may be formed. 
Persons sensitive to formalin are cautioned against the toxicity of 
paraformaldehyde, especially against inhaling its dust. (This section on 
paraformaldehyde paraphrased from Huheey, 1963, and Taub, 1962.) 
Ethyl Alcohol 
Ethyl alcohol is also called ethanol, grain alcohol, or spirits of wine. 
(Wood alcohol, methyl alcohol, or methanol as it is variously called is a 
poor preservative; it is poisonous, while undenatured ethyl alcohol is not.) 
Ethyl alcohol is ordinarily obtained as 95 per cent (66.6° overproof) un- 
matured undenatured ethyl alcohol. To preserve fishes in ethyl alcohol, the 
preservative must be gradually brought up to the 70 per cent concentration; 
otherwise the fishes will shrink. An alcohol hydrometer or alcoholometer is 
essential for preserving with ethyl alcohol. The alcohol percentages given 
below are by weight, but for simplicity the volume measures necessary to make 
them up are given. The following concentrations are required for preserving : 
(a) 50% ( = proof spirit) made with 9 volumes of water to 10 volumes 
of 95% alcohol 
(b) 60% alcohol (20° overproof) made with 6 volumes of water to 10 
of 95% alcohol 
(c) 70% alcohol (40° overproof) made with 3 volumes of water to 10 
of 95% alcohol. 
(See also the British Museum Instructions for Collectors No. 13. Alcohol 
and alcoholometers.) Note that when alcohol and water are mixed, some 
shrinkage in total volume occurs. 
Freezing 
Quick freezing (best at about 10° F) is an effective mode of preservation. 
Colour is retained. Large specimens can be dealt with by freezing. The 
specimens may be thawed out later in 10 per cent formalin, or in water 
and then fixed in formalin. 
