RECIPES, FORMUL& AND USEFUL HINTS. 143 
Peron’s Luting. 
Common resin 
Red cchre 
Yellow wax 
Oil of turpentine 
First melt the wax, then add the resin, next stir in the ochre and 
lastly the turpentine. According as the ochre or other ingredients pre- 
dominate, the luting will be brittle or elastic. | Great care should be 
taken that the mixture does not take fire and the vessel used should be 
capable of containing at least three times the quantity made at one 
time. 
Grafting wax. 
Melt together eight oz. resin, three of beeswax and one of lard. Run 
in sticks. It improves with age. 
Black ink. 
A black ink is frequently desirable and is almost impossible to obtain 
in the stores. A good ink may be made by boiling eight oz. of pow- 
dered nut galls and one oz. extract of logwood in three quarts of water 
for an hour. Strain and add four oz. of copperas (sulphate of iron), 
three oz. of gum arabic and one of blue vitriol (sulphate of copper); 
let it stand until dissolved and strain again. A few cloves will keep 
it from moulding. 
Old alcohol which has been discolored by specimens can be cleaned 
by filtering through animal charcoal, but nothing will completely remove 
disagreeable odors though a redistillation will sometimes help it. 
After filtering, the spirit should be brought to a proper strength (to be 
ascertained by the hydrometer) by adding new alcohol. 
To blacken brass. 
It is occasionally desirable to blacken portions of instruments as stages 
of microscopes, etc. This may be done by cleaning the brass of all 
grease, then covering with a solution of nitrate of copper which on the 
application of heat turns the surface to a jet black. If desirable, it may 
then be lacquered by applying shellac varnish and heating slightly. 
