243 TAGG—NOTES ON MUSEUM-METHODS 
For softening material already hardened it is to be preferred 
generally to the 50 per cent. water-solution often employed for 
the purpose. The glycerine tends to keep the material pliable 
without exerting the macerating action that water under similar 
circumstances with delicate specimens is inclined to do. 
It has been employed with some success for succulent speci- 
mens causing less contraction in such than alcohol does alone. 
For this purpose the following formula is used :— 
go per cent. Alcohol, : 50 C.c. 
= eae : : : : 50 c.c. 
Glycerine, 50 c.c. 
ad. Synthol. 
Recently an alcoholic preparation called synthol has been 
recommended as a preservative for museum purposes. 
It is claimed for it that it is a perfect substitute for absolute 
alcohol, and that it is an excellent dehydrating agent and a 
preservative of the first order. 
From experiments I have made with it absolute synthol appears 
to act efficiently as a substitute for absolute alcohol. 
For museum purposes, used undiluted, it penetrates and hardens 
delicate tissues rapidly and at the same time bleaches them as 
effectively as strong methylated alcohol. Diluted with water its 
action is less rapid, while the weaker percentages, as with alcohol 
proper, fail to harden. Photoxylin can be used with it as a 
mounting medium, but gelatine contracts and becomes opaque. 
2. AQUEOUS SOLUTIONS, 
a. Formalin. 
Formol, formalin, formaline are commercial names for a 40 
per cent. solution in water of formaldehyde, CH,O. As a 
preservative the commercial preparation is used undiluted, or 
diluted with water to whatever extent required. The solutions 
which have been found most useful are—formalin 10 parts: 
water 90 parts; and formalin 15 parts, water 85 parts. Weaker 
solutions have been tried, but with them moulds in nearly all cases 
make their appearance on the surface of the fluid. The weaker 
solutions prove less reliable the larger the bulk of organic substance 
