THE YOUXG SCIENTIST. 
15 
PRACTICAL JfOTES. 
X«fc.— In the recipes generally given for making 
ink, it is recommended to boil the ingredients. This 
is a very serious mistake. It should always be made 
with cold water. By this latter process, more time is 
of course necessary to make it ; but then the ink is 
very superior, and entirely free from extractive matter 
which has no inky quality, and which only tends to 
clog the pen and to turn the ink ropy and mouldy. 
Take gallnuts, broken, one pound ; sulphate of iron, 
half a pound ; gum acacia and sugar candy, of each a 
quarter of a pound ; water, three quarts. Place the 
whole of these ingredients in a vessel where they can 
be agitated once a day ; after standing for a fortnight 
or three weeks the ink is ready for use. Logwood and 
similar materials, are often advised to be used in con- 
junction with the gallnuts, but they serve no good 
purpose unless it be to make a cheaper article which 
fades rapidly. 
Clay for Modelling and Terra Cotta.—lu an- 
swer to a correspondent, the Druggist's Circular gives 
the following information on this subject : Any kind of 
good plastic clay will answer, and it is of no consequence 
if it contains iron even in large pi'oportions. Only it 
must be freed from stones and coarse sand by means 
of elutriation, and be well kneaded together to insure 
homogeneousness. A mixture of glycerine and water 
was at one time proposed to moisten modelling clay, so 
as to avoid the necessity of constantly wetting the 
models, but it is said that the process is unsatisfactory, 
as the clay on drying allows the glycerine to escape in 
■drops. In technical parlance, it " sweats out." For 
terra cotta, clay containing too much iron is undesirable 
because, on baking, it assumes a glaring brick-red 
color. But a moderate proportion of the metal imparts 
to the finished objects a very pleasing color. Of course, 
glycerine is quite out of place in clay that is to be 
baked. 
Varnishing Wood. — A good surface may be pro- 
duced on unpainted wood by the following treatment : 
glass-paper the wood thoroughly as for French polish- 
ing, size it, and lay on a coat of varnish, very thin, with 
a, piece of sponge or wadding covered with a piece of 
linen rag. When dry, rub down with pumice dust, and 
apply a second coat of varnish. Three or four coats 
«hould produce a surface almost equal to French polish, 
if the varnish is good and the pumice dust be well ap- 
plied between each coat. The use of a sponge or wad- 
ding instead of a brush, aids in preventing the streaky 
appearance usually caused by a brush in the hands of 
an unskilled person. — Artizan. 
Metallic Soap for Canvas. — The following is 
highly recommended as a cheap and simple process for 
■coating canvas for wagon tops, tents, awnings, etc. It 
renders it impermeable to moisture, without making it 
-stiff and liable to break. Soft soap is to be dissolved in 
hot water, and a solution of sulphate of iron added. 
The sulphuric acid combines with the potash of the 
soap, and the oxide of iron is precipitated with the fatty 
acid as insoluble iron soap. This is washed and dried, 
and mixed with linseed oil. The soap prevents the 
•oil from getting hard and cracking, and at the same 
time water has no eflFect on it. 
Tracing I*atterns. — When a few duplicates of pat- 
terns for embroidery are required, they may be very 
easily made by hand as follows : 
The drawing is made upon paper ; then lay the draw- 
ing upon an even cloth, and perforate all the lines with 
a fine needle, close and even. Then take finely pow- 
dered charcoal, three parts, resin one part in fine pow- 
der; mix and tie it in apiece of porous calico, so that 
it forms a dusting bag. Lay the perforated drawing 
upon your material, hold down with one hand, rub the 
dusting-bag over the drawing ; the dust will fall 
through the holes and form the drawing on the mate- 
rial. Remove the paper drawing, lay blotting-paper 
over the dust pattern, and go over it with a warm flat- 
ting iron. The heat will melt the resin and fix the 
drawing on the material. 
I'^'ire Kindlers.—A writer in the Neiv England 
Farmer says that pine needles make the best fire kind- 
lers he has ever used. In northern regions they may be 
gathered in the woods in any quantity, and if kept 
under cover and dry, they are far ahead of shavings, 
whittliugs, etc. As they contain a very large proportion 
of resin, the suggestion deserves attention. 
Superior Paste.— It is said that a paste made of 
seven parts of gum tragacanth and one part of gum 
arable, with a few drops of oil of cloves, or diluted car- 
bolic acid, will be found very reliable. It adheres 
strongly and does not turn sour like book-binder's 
paste, which is made of flour. 
Soldering Fltiid.—lt is said that a solution of 
phosphoric acid in alcohol makes an excellent soldering 
fluid, which has some advantages over chloride of zinc. 
BOOK NOTICES. 
The Young Chemist, — A book of Laboratory Work 
for Beginners, By John H. Appleton, A. M., Professor 
of Chemisti-y in Brown University. Second Edition. 
Philadelphia : Cowperthwait & Co. 
The importance of experimental illustration of the 
scientific facts brought to the attention of pupils, has 
been long acknowledged by all educators of intelli- 
gence. One good experiment is worth an hour's talk, 
and a single glance through a microscope at a good 
preparation is w^orth pages of description. Professor 
Appleton has therefore done a good work in endeavor- 
ing to smooth the path of teachers and pupils in this 
direction, but we wish he had brought the experiments 
within the reach of a wider class than he has done. 
While there are many valuable suggestions in the book, 
there are many points which might have been simpli- 
fied, and although he says himself that one objection 
to the introduction of the experimental method is the 
cost of supplies, his apparatus is not always as cheap as 
it might be without reducing its efliciency. Side neck 
flasks and test tubes are very good, but it is not every 
teacher that can make them, and they can be procured 
only from dealers in large cities. Common test tubes, 
and what is called quill tubing, may be had from any 
druggist, and the teacher who cannot make gas-appar- 
atus out of these and a good cork, had better not try to 
experiment. So, too, the leaden saucer used for prepar- 
ing fluorine (page 30), must be procured from a dealer ; 
while a saucer, equally good, might be made by the 
teacher himself, if a figure of it had been given. 
