852 
•Sht RURAL. NEW-YORKER 
April 24. 1020 
Simple Science 
By Dr. F. D. Crane 
Duplicating Blue Prints 
IIow can I duplicate from blueprints? 
Buffalo, N. Y. c. w. b. 
Something depends upou the blueprint. 
Some are deep enough to print fairly Avell 
directly, giving you a blue line on white 
ground print, which may, in its turn, be 
printed from. Some have to be toned by 
bleaching in a one-half of 1 per cent solu¬ 
tion of caustic soda in water, which gives 
a pale yellow print, which is then black¬ 
ened in a one-third of 1 per cent solution 
of tannic acid in water. This, if the 
blueprint is fairly good to start with, will 
print clear and deep blue lines on a white 
ground, and this print, in turn, can be 
blackened and will give you something to 
print from. 
Another plan is to make a pale blue¬ 
print, just enough to see where the lines 
are, and go over each white line with the 
best drawing ink. This can be used di¬ 
rectly to print from. As the pale blue 
ground will hardly hold back any light, the 
time of exposure is very slightly longer. 
In any event, you would better practice a 
little on a blue-print you care nothing for, 
so as to see now the change of color 
works. 
Copying Pad 
How can I make a letter copying pad? 
Oakville, Can. b. f. t. 
The principle on which these are made 
is to dissolve previously water-swollen 
glue in glycerine, which should be heated 
in a water bath of salt-saturated water 
(2 o55. common salt to the pint), and stir 
in a little kaolin or barytes. You can get 
the latter at a paint store under the name 
Blanc fixe. Out of a bunch of formulas, 
all about alike, we pick one for tin dish 
7x11 in. Clue, 3 oz., water, 11% oz., 
glycerine, 15 oz.. kaolin or barytes, % oz. 
Soak the glue in the water over night, 
pour off' the excess water, if any, and dis¬ 
solve in the glycerine heated in the water 
bath mentioned, stirring in the kaolin and 
pouring into the pan. Stir under heat for 
an hour before pouring. Add a few drops 
oil of cloves to preserve. Wash the pad 
lightly before taking the first copy. 
gone out of business. At present pas¬ 
teurization is the only sure method. 
Wax for Sealing Cans 
What kind of wax is used to put on 
strings to seal gasket-top tin cans? 
Could graftiug wax be used? w. n. w. 
Stroudsburg, Pa. 
As we have never seen a sample of 
that string wax we will have to refer 
the matter to our readers, but we are 
quite certain that grafting wax could not 
be used. If you want to sell your sur¬ 
plus grafting wax you might put a fair 
price on it and try an advertisement of 
a couple of lines in our Subscribers’ Ex¬ 
change. 
Tomato Vinegar 
Is tomato vinegar desirable for table 
use. or only for pickling? Can it be made 
at home without special equipment? "What 
is the formula and method? w. r. D. 
This question was asked last year, and 
we made a trial lot. It is possible to fer¬ 
ment tomato juice and then put it through 
the acetic fermentation and get a vinegar, 
but not a very attractive article. After 
this had been published one of our friend* 
sent in a formula by which, it was said, 
many gallons had been made both for 
home use and for sale. But you will note 
that it is really a brown sugar vinegar in 
which the nutrients, other than sugar, re¬ 
quired by the yeast, are furnished by to¬ 
mato juice. This would no doubt give a 
sufficiently sour vinegar with a flavor de¬ 
rived from the tomato. No special equip¬ 
ment is required for small lots, and for 
larger lots only larger containers, so if 
you are so unfortunate as to he unable to 
get. cider and so fortunate as to have 
plenty of ripe tomatoes, it might be worth 
a trial. But beware of the tomato which 
has a speck in it or is just getting too 
soft, or the whole lot may decay instead 
of fermenting. The formula as sent in 
follows: “Take ripe tomatoes, mash them 
up any way—I run them through cider 
mill—but don’t press them. Put them In 
a coarse bag; a fertilizer bag, well washed 
out, is what I use. Hang it up and let 
drain over night, and if you find a little 
squeeze on the bag will bring more juice, 
all right. Let the juice stand till it »et- 
tles some, then pour off into another tub 
or keg, add enough heavy molasses to give 
it the color of dark cider, with a decided 
sweet taste. Set away in a warm place, 
outdoors if you wish, but cover so as to 
keep rain and flies out. Don’t use any 
“mother’* in it. When cold weather come* 
rack it off into clean barrel or keg. I have 
made and sold hundreds of gallons. It 
looks and tastes very much like pure cider 
vinegar.” 
Phosphate Baking Powder 
What is a receipt for a phosphate bak¬ 
ing powder. J. B. 
We do not think much of that sort of 
powder, but if you must make it. here are 
the proposition : Acid calcium phosphate 
2 lbs., powdered exsiccated alum 2 lbs., 
sodium bicarbonate ,3 lbs., starch .3 lbs. 
Mix 1 lb. of the starch with each of the 
other three ingredients and then mix all. 
The purpose of this is to coat the active 
ingredients with the inert starch so that 
they will not react till wet in use. You 
may better mix % lb. of starch with 2 lbs. 
of cream of tartar, another % lb. of starch 
with 1 lb. of bicarbonate of soda and then 
mix the two mixtures. This will give you 
a good tartar powder which will stand 
considerable more starch if you wish to 
add it. 
Removing Varnish; Cleaning Marble 
What will take varnish off walnut fur¬ 
niture? What will talcs stains off white 
marble A,*. 
Crisfield, Md. 
A good deal depends upon the kind of 
varnish. Try equal parts benzene, (if 
yon can get it, also known as benzol, but 
not benzine), nnd denatured alcohol, 
made slightly alkaline with n little am¬ 
monia water. This should be swabbed 
on. allowed to remain a few moments and 
rubbed off. You will have to use some 
observation, and fit the treatment to the 
thickness of the coat of varnish. If you 
can not get benzol, use the denatured al¬ 
cohol with just a little lye in it, and be 
more cautious. The very best way to 
take off varnish is by rubbing with steel 
wool, but it is a lot of hard work and, in 
the case of carved Lgs. almost impossible. 
There are some varnishes which are al¬ 
most insoluble, but usually will give way 
in time. As long as the varnish is there 
the wood will not be discolored, the trick 
is to stop the treatment just as you hav* 
the varnish off. In the case of the mar¬ 
ble, so much depends on the sort of stain 
that a long distance guess is not much 
good. The surface usually has to be re¬ 
polished as a whole, which is hard work. 
Very weak hydrochloric (muriatic) arid 
will take off the surface of marble and 
the stain with it, but will leave a rough 
spot which must he polished. 
I 
Waterproofing Canvas 
We have a canvas vehicle cover which 
picks up water, and tin- cost of oil makes 
its use prohibitive. What can he done? 
Oxford, N. Y. c. M. 
If the canvas is not worth the oil it is 
likely not worth much time or anything 
else, but you might try painting it with 
a rather tliiu glue, and then, without 
waiting for it to dry, with a solution of 
chrome alum of the same strength, by 
weight, as the glue. Once set. this coat¬ 
ing is insoluble in water, and if you do 
not use too strong a glue solution the can¬ 
vas will not he much stiffened. Better 
try a small amount of eacli solution on 
some old hit of canvas first. If you get it 
on too stiff' it will crack the canvas. 
“New Skin Grower” 
What is “new skin grower”? A. s. 
Sabina, O. 
One of the varieties of flexible collo¬ 
dion. which is made by adding castor oil 
or glycerine in small proportions to or¬ 
dinary collodion. The latter is a solution 
of a special sort of nitrated cotton in 
equal parts of alcohol and ether. So lit¬ 
tle is used by the ordinary family that it 
is not worth while to make it yourself, 
and as the solvents evaporate readily, it 
should be purchased in small portions. 
Ask for “flexible collodion” at any good 
drug store, and use it on small cuts and 
scratches after treatment with iodine to 
disinfect them. But do not use it with¬ 
out previous disiufectiou of the injured 
surface 
Paste for Wallpaper; Disinfectant 
What is a good paste for wallpaper, 
and what disinfectant could be used? 
A. J. 
Several recipes have appeared pre¬ 
viously in The R. N.-Y., but the best 
general results seem to he from a paste 
of rve flour, which is made by stirring 
the flour into warm water and continu¬ 
ing to stir till the mixture is perfectly 
smooth, and free from even small lumps. 
This paste is then brought to a boil under 
constant stirring and allowed to cool. 
Burning can be avoided by using a dou¬ 
ble boiler with saturated salt water iu 
the outer container. The exact amount 
of flour must be found by trial, as flours 
differ in their paste-making ability. A 
little carbolic acid will preserve this 
paste very well and act as a disinfectant. 
Pasteurized Cider 
What about a process for preserving 
cider by treating it with carbon dioxide, 
and thus doing away with pasteurization? 
Viuemont, Pa. w. J. s. 
Carbon dioxide alone will not work. 
We do not know anything about the 
special process you mention, but the con¬ 
cern which was pushing it seems to have 
lirtinniiitniniifntiminiiiniiiniiiHiiiiiiimitininnininnrimmiiiiinniiniiniiiinfiimflii is 
I N farm service, Garfords are earning 
profits because they haul on a basis of 
Low Cost Tort-Mile. Returns from a re¬ 
cent investigation among 4,000 Garford 
owners showed 97.6% are 100% sat¬ 
isfied. Let us send you their records 
covering every kind of haulage. 
That the United States Army htts made Garford a Class A 
Standard is another proof of Garford servicabihty 
