21 
For large collections of skulls as well as for specimens preserved in 
liquids it is convenient to have small tags of pure sheet fin or Monel-metal 
stamped with serial numbers. These tags should be attached to the 
specimens with Monel-metal wire, which is not affected by water nor 
corroded by other liquids. 
Liquid Preservatives 
Alcohol and formalin (formaldehyde) are most commonly used for 
preserving specimens entire, or for any soft parts, stomach contents, etc., 
that are desirable to keep. Denatured alcohol or wood alcohol (methyl 
hydrate) will do for ordinary purposes, but the fumes are disagreeable 
and often contain acids that tend to decalcify the bones in the course of time. 
Grain alcohol (ethyl alcohol) is more agreeable to handle and less 
poisonous, but is more expensive. The alcohol should be at least 85 per 
cent. If the alcohol is too strong it hardens the tissues, and if it is too 
weak they decompose, so the better error is on the side of strength. 
Alcohol or formalin will not readily penetrate thick skins, so that specimens 
should be cut open on the abdomen before immersion, so that the preserving 
fluid can get inside. Otherwise a specimen may look good on the surface, 
but be rotten inside. 
All zoological specimens contain a large percentage of water. This is 
replaced by the alcohol, weakening the solution, so that specimens should 
not be crowded until they are thoroughly pickled. After the specimens are 
well preserved, they may be packed more closely, and in some cases the 
strength of the alcohol may be reduced. If large quantities of alcoholic 
specimens are to be collected, the collector should have an alcoholometer 
for testing the strength of the spirits from time to time. 
Formalin has some advantages, not the least of which is the light 
weight. The ordinary commercial solution is about 60 per cent water. 
For ordinary purposes this is diluted with nine parts of water to make a 
4 per cent solution, which may be made either stronger or weaker according 
to the climate and the nature of the specimen. One great drawback to its 
use in northern latitudes is that the diluted solution will freeze as easily 
as water and burst the bottle or containers if they are filled too full. 
Specimens preserved in either alcohol or formalin become hardened so that 
they are hard to skin. Formalin also has the disadvantage of contracting 
the tissues and of bleaching out the colours. Some complaint is made that 
formalin dissolves the calcium and softens the bones of specimens that are 
immersed in it for any length of time. 
Dr. G. S. Whitby, formerly Director of the Division of Chemistry, 
National Research Council, Ottawa, was consulted on the subject of 
neutralized formalin, and the following statement was received: 
"If it has been found that neutralized formalin has not the softening effect of 
ordinary formalin on bones and shells of mollusks it would probably be found more 
practical and less costly to neutralize the free acid present in commercial formalin 
rather than ask the formaldehyde manufacturer to do it. In formalin intended for 
general use the presence of small amounts of formic acid is not objectionable. The 
practice of adding potassium nitrite to the embalming solution used for preserving 
cadavers intended for dissection might give good results in the case of formalin 
solutions for preserving museum specimens. Embalming solutions contain 12-20 per 
cent formaldehyde, 10 per cent glycerol, and 0-1 per cent potassium nitrite. The 
object of adding nitrite is probably to oxidize any formic acid present to CO 2 (carbon 
