30 THE YOUNO 
is an old one, or else they will flake off; wrap 
the feet and legs with wet cloths as described 
above, and let the skin lie without other wrap- 
ping for one day. At the end of this time the 
joints can be bent somewhat, and they should 
be manipulated until they bend easily. When 
they will do this, put wet cloths round the joints 
of the wings— in the body, neck, and head, and 
wrap the whole skin in a wet cloth. At the end 
of the second day the entire skin will be soft. 
The next step is to scrape all the hard parts of 
the skin and manipulate it until it is as soft as 
when fresh. 
This process applies, with slight modifica- 
tions, to all large bird skins, but, of course, the 
larger the bird, the longer it will take to relax. 
Sometimes the wings require soaking half as 
long as the legs in very large birds but care 
must be taken not to soak any feathered parts 
too long or the feathers are liable to drop out 
and cause serious trouble. 
By the above process, skins may be softened 
and mad^ ready to mount according to their 
size, about as follows : Wren to robin, in twelve 
to fourteen hours; ruffed grouse, two days; 
great blue heron, three days ; bald eagle, four 
days; condor, five days; ostrich, six to eight 
days. Skins which are but a few months old 
will soften in about half the time they would re- 
quire were they five years old, and if properly 
made in the first place will make as handsome 
mounted specimens as fresh skins.— W. T. H., in 
Ward's Natural Science Bulletin. 
Cleaning and *' Dipping" Brass. 
The following process is said to be in use in 
the government arsenals: Make a mixture of 
one part common nitric acid and one-half part 
sulphuric acid in a stone jar ; then place ready 
a pail of fresh water and a box of saw-dust. Dip 
the articles to be cleaned in the acid, then re- 
move them into the water, after which rub 
them with saw- dust. This immediately changes 
them to a brilliant color. If the brass is greasy 
it must be first dipped in a strong solution of 
potash and soda in warm water. This dissolves 
and removes the grease so that the acid has the 
power to act. 
Dyeing Ivory. 
Almost all articles made of ivory look best 
when this material is left of its natural color- 
pure white. For some purposes, however, a 
contrast of color is desirable, and in such cases 
recourse must be had to dyeing. The following 
formula have been found to give good results. 
It is well to note that unpolished ivory takes 
color better than polished. Ivory must not be 
boiled long in liquids, and, according to Kar- 
SCIENTIST. 
marsch, when taken out of hot liquid should 
be rapidly cooled by laying in cold water. Ivory 
is very sensitive to change of temperature, and 
while it will stand the treatment just menr 
tioned, will not stand forcible blows w^hen cold 
1. Black. Boil for a short time in a strained 
solution of logwood, afterwards immerse in a 
solution of green sulphate of iron. 
2. Blue. Immerse for a short time in a dilute 
solution of indigo-carmine. 
3. Yellow, a. Immerse for a few mintites in 
water containing a little stannous chloride 
(protochloride of tin) ; afterwards in a hot, 
strained decoction of fustic. 
h. Immerse for about fifteen minutes in a so- 
lution of chromate of potassium. . 
4. Orange. Treat as in the first process for yel- 
low, but add to the fustic some shavings of 
Brazil-wood (Pernambuco-wood). 
5. Red, a. Macerate cochineal in vinegar, and 
boil the ivory in the liquid for a few minutes. 
h. Carmine dissolved in ammonia may be 
used. The tint is more purple-red. 
c. Immerse in a very dilute solution of stan- 
nous chloridp, and afterwards in a boiling solu- 
tion of Brazil-wood. A little fustic turns the 
color to scarlet. 
d. Ivory dyed as last directed is rendered 
cherry-red by immersion in a very dilute solu- 
tion of potash. 
e. Im merse in an alcoholic solution of alizarin- 
paste. 
6. Violet, a. Dye red first ; then immerse for 
an instant in solution of indigo-carmine. 
5. Macerate in dilute solution of stannous 
chloride ; then dip into a hot decoction of log- 
wood. If the article be afterwards laid in water 
acidulated with a few drops of nitric acid, the 
color turns purple-red. 
7. Green, a. Dye first yellow, and afterwards 
dip into solution of indigo-carmine. 
h. Place for several hours in concentrated so- 
lution of chromate of potassium; afterwards 
expose to sunlight; this produces a dark, 
bluish-green tint. 
Blue Prints.— An improved method of making 
eyanotypes, which gives a blue picture Avith a 
pure white ground, is described by Eder. 
Well-sized paper is painted over with a brush 
with the following solution, freshly prepared; 
30 volumes of gum Arabic solution (l to 5). 8 
volumes solution of citrate of iron and ammonia 
(1 to 2), 5 volumes solution of perchloride of iron 
(1 to 2). The mixture appears limpid at first, but 
soon grows thicker. 
The paper is dried in the dark, then exposed 
