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strengthened to a certain extent by treating them with a thin solution of 
gum arabic in water. In other cases the celluloid solution will be found 
better. Any spare beads should be carefully kept, their utility in repair 
work being very great and the difficulty of buying beads to match a certain 
size and colour being considerable. 
Clay 
Soft clay specimens, as distinguished from baked clay or pottery, are 
rare in Canadian anthropology. They obviously cannot be washed and 
there is only one satisfactory method of treatment available. The speci- 
men must be cleaned as much as is practicable and then fired in a kiln. 
The assistance of somebody experienced in the firing of pottery should be 
enlisted, unless the preparator is already familiar with this operation. A 
slight change in the size and appearance of the specimen is inevitable, but 
this is to be preferred to its loss, which is certain if firing is not resorted to. 
After firing, it is usually possible to clean the specimen more completely 
by mechanical methods, if it seems desirable. 
Copper 
There are probably several dozen so-called “recipes" for the cleaning 
of copper and bronze available, many of them harmful or useless. In deal- 
ing with copper specimens two possible conditions confront the preparator: 
they may be so badly corroded that little or none of the original metal is 
left; or, there is more or less unsightly patina and corrosion product which 
has to be removed. 
Badly corroded specimens, where the original metal is largely eaten 
away, are beyond cleaning, save for the removal of superficial adherent 
dirt, except by electrolysis. The best plan is to prevent further corrosion 
by giving the object a preservative coating. First, the specimen should 
be washed in several changes of water, to make sure of the elimination of 
all soluble salts. When this treatment is found, on testing with silver 
nitrate, to be complete the specimen should be well dried and then dipped 
in a solution of celluloid in acetone, where it remains until no more air 
bubbles can be induced to rise to the surface when the object is moved or 
turned over. It is then dried and the celluloid bath repeated if desirable. 
Specimens in this condition should give no further trouble, even though 
their appearance may be unsatisfactory. 
When specimens are less severely affected, corrosion products and 
patina may be removed in either of two ways : by the use of Rochelle salts, 
or by the use of acetic acid. The Rochelle salts method is easy of applica- 
tion and quite satisfactory. The formula published by Lucas is an alkaline 
solution of Rochelle salt (sodium potassium tartarate) containing 15 parts 
of Rochelle salt and 5 parts of caustic soda to 100 parts of water. The 
specimen should be allowed to soak in the solution for several hours or 
even a day or two and then rinsed and brushed with a stiff brush. A brass- 
wire (not steel-wire) brush may be used if it is found not to be too severe 
in its action. The specimen may be coated with a layer of red oxide that 
should come off with brushing. A second bath in a fresh solution of the 
same salt should be followed by thorough washing and drying. If the 
specimen appears to be too bright in colour it may be allowed to stand in 
ordinary room atmosphere for a time until a slight tarnish appears, when 
it is to be coated with the celluloid solution. 
