THE YOUNG SCIENTIST. 
79 
1 done good service by giving simple and yet very 
I complete directions for all the operations con- 
' nected with section cutting. To the American 
edition has been added notes eaual in amount of 
matter to quite half the original work. These 
not only explain such English terms as Rangoon 
oil, etc., but give a very complete and fully illus- 
trated article on the selection and keeping in 
order of section knives. 
Liquid G-lue.— Dilute officinal phosphoric acid 
with two parts, by weight, of water, and saturate 
with carbonate of ammonia ; dilute the resulting 
liquid, which must be still somewhat acid, with 
another part of distilled water, warm it on a water- 
bath, and dissolve in it enough good glue to form 
a thick, syrupy liquid. It must be kept in well- 
closed bottles. 
Coppering: Iron or Steel.— The following 
process is said to give very good results : First 
make the article entirely bright by file, scratch 
brush, or any of the usual modes. Apply to the 
surface a coating of cream of tartar, then sprinkle 
the surface with a saturated solution of sulphate 
of copper, and rub with a hard brush. The coat- 
ing of copper deposited on the iron is said to be 
very even and durable. 
Cleaning- G-lass Bottles.— It is stated that 
glass bottles may be quickly and thoroughly 
cleansed from all traces of adhering fatty or oily 
matters by the use of a concentrated solution of 
permanganate of potash to which a few drops of 
hydrochloric acid are added. The solution is em- 
ployed by washing and rinsing. The hydrochloric 
acid sets free a little caustic potash, which in 
some way appears to be more active in its effect 
upon the oily or greasy matters than, when pre- 
sented in the ordinary way. We wish it under- 
stood that we do not vouch for the value of this 
recipe. We reproduce it from the Druggists' Cir- 
cular merely as a hint which may be cheaply 
tried. 
Standard Measures.— The standard yard, now 
in use in the United States, was taken from the 
English standard yard ; but it was subsequently 
shown that this standard, as deposited in the 
oface of weights and measures at Washington, 
was incorrectly taken off— it being 0.00005803 longer 
than the English imperial standard yard. This 
difference was no doubt due to incorrectness of 
the divisions on the original scale, or derived 
from insufficiently delicate appliances for read- 
ing off the measure from the English standard. 
It cannot be expected that the divisions on the 
English scale could be very correct, from want of 
knowledge in those days to make a correct screw, 
which is yet a difficult problem, even with our ad- 
vanced knowledge of mechanic arts. But as it 
was originally intended to have the English and 
American standards of length alike, we ought not 
to acknowledge any difference. 
The Smithsonian Institution published tables 
in 1859, comparing the length of the English and 
American foot measures, which makes the Ameri- 
can yard 2-lOOOth parts of an inch longer than the 
Imperial standard yard, or a difference of four 
inches per mile. The United States Coast Survey 
are now using a corrected American standard; 
yard, the same length as the Imperial standard 
yard.— JowmaZ Franklin Institute. 
Bronzing Wood, Leather, Paper, Etc.— The 
Monitear Industriel, of Paris, describes a process 
for bronzing wood, leather, paper, etc., as follows: 
The inventor dissolves gum lac in four parts by 
volume of pure alcohol, and then adds bronze or 
any other metal powder in the proportion of one 
part to three parts of the solution. The surface, 
to be covered must be very smooth. In the case 
of wood, one or several coats of Mendon or Span- 
ish white are given, and the object is polished 
with an iron of proper shape. The mixture is 
psinted on, and when a sufficient number of coats 
have been given, the object is well rubbed. A 
special advantage of this process is that the coat- 
ing obtained is n(5t dull, but can be burnished. 
A transparent varnish is applied to preserve the 
metallic appearance thus obtained. 
"Washing- G-lass.- The following hints apply 
to glass slides used in microscopy, as well as to 
chemical vessels. A correspondent of the Chem- 
ical J}^ews says: Such a subject may seem too- 
simple, but yet the more I see students at their 
work, the more I am impressed with the fact that 
but few know how to wash a beaker-glass clean.r. 
Some time since I took beakers from various 
students in my laboratory (which they had 
washed and put away), and helcl them under a 
powerful stream of water until thoy were thor- 
oughly wet. On taking them from under the 
spout, in almost every case the water ran off the 
glass in spots, showing that the glass was greasy. 
The best thing to wash beakers, etc., with, ac- 
cording to my experience, is sand-soap. Natur- 
ally, the sand must not be sharp. The soaps con- 
taining infusorial earth are most excellent for 
this purpose. Borax soap is also very efficacious^ 
A piece of board about 20 cm. long, 15 cm. wide, 
and 4 cm. thick, should be screwed on to the right 
(inside) of the sink. In this block a rectangular 
hole, about 2 cm. deep, and 1 cm. smaller than the 
section of the soap when stood on its long end, is 
to be cut. The bottom of the cake of soap is then 
whittled away so that it fits tightly in the hole. 
It is now moistened and pushed into the aper- 
ture, where it remains tightly fixed. By wetting 
the right hand thoroughly, and rubbing on this 
soap ridge, a good lather is made. With the 
soapy hand the glass is rubbed and washed until, 
on taking it from under the stream, no oily spots 
appear, the glass appearing wet all over. The 
beaker is then dried with a good towel ("glass 
towel"), and finally polished with a piece of 
chamois or kid leather. The final polish with 
kid is necessary, since the best towel leaves fibres 
on the glass. In cleaning test tubes, it is only 
necessary to rub the probang on the soap. 
