Vol. XXIV. No. ii.] 
POPULAR SCIENCE NEWS. 
16 
Practical dienjistry ar^d tlje }Irts. 
SOME NEW LABORATORY DEVICES. 
The following simple, but useful forms 
of laboratory apparatus are' described and 
' illustrated in the American Druggist, which 
journal has collected them from their original 
sources. Practical chemists will find them 
' exceedingly useful for the purposes for which 
they are designed. 
A Modified Form of Pinciicock. — As is 
shown in the cut, the modification consists in 
making a side bend in one of the limbs and 
omitting the double wire which serves as a 
guide in the ordinary form. The pinchcock 
can be opened by springing the limbs apart, 
and thus is readily put on a tube connected at 
; both ends without bre/iking connections, and, 
when placed so that the tube lies in the side 
, bend, leaves the tube open while retaining its 
place. — J. T. Stoddart. 
A Self-supporting Absorption Tube. — 
! Stolba uses absorption tubes (for drying gases, 
t etc.) of the shape shown in the cut. A por- 
tion of the tube is bent into a flat spiral, upon 
which it rests when placed on the laboratory 
table. The two tubes passing through the 
•' stoppers are closed at the inner orifice, but 
have an aperture a short distance above the 
end. It is only necessary to draw up either 
1 1 tube so that the aperture is within the stapper, 
when the current of gas will cease to pass. 
A New Test-tube Holder. — The an- 
noyance experienced in using the common 
wooden test-tube holders Jed me some years 
ago to attempt to devise a holder which 
should serve its purpose more perfectly. The 
wooden holder is clumsy, its rubber band 
rots and is liable to give way at awkward 
moments, the peg becomes unglued and 
drops out, and even in its best estate it holds 
securely only medium-sized test-tubes. Tubes 
of more than 2 cm. cannot be inserted side- 
ways, larger ones are not taken at all, and a 
separate holder must be used for small test- 
tubes and ignition-tubes. The new holder is 
made of brass wire, and opens by pressure 
on the straight sides of the handle. Its jaws 
open to the width of 5 cm., and it holds 
firmly any tube from 5 mm. up. It thus 
serves' for ignition-tubes as well as for all 
sizes of test-tubes. I have recently had a 
larger size made of stifier wire for the pur- 
pose of holding flasks, etc. It proves very 
convenient as a holder of wash-bottles when 
one is washing with boiling water, and also 
for holding beakers when decanting hot solu- 
tions. — J. T. Stoddart. 
A New Valve for Wash-bottles. — In 
view of the fact that metallurgical and techni- 
cal chemists have daily occasion to use hot 
acids, ammonia, and other fuming liquids in 
the washing of precipitates, a wash-bottle 
which will automatically throw a prolonged 
stream of liquid and retain all disagreeable 
gases will be appreciated by the fraternity. 
A strong objection to the use of a rubber 
bulb attached to the wash-bottle is the fact 
that a slight rise in the temperature of the 
room will force the liquid out of the bottle ; 
while the ordinary rubber valve, as described 
by Blair in the "Analysis of Iron," will swell 
and become useless in a short time when 
exposed to the fumes of hot acids. A very 
simple apparatus can be made in a few 
minutes which obviates both these difficulties. 
A rubber stopper, doubly perforated, and 
of such size that it will project about a 
quarter inch above the neck of the wash- 
bottle, is chosen, a lead pencil or penholder 
passed into one of the holes, and a small 
hole drilled through the side of the stopper 
till the borer meets the wooden plug. A 
wedge-shaped channel is then cut in the side 
of the stopper from this side hole to its lower 
end. A piece of glass tubing is now closed 
at one end, and a small opening about the 
size of a pin's head made in the glass an inch 
from the closed end. This can be easily done 
by a small flame directed upon the surface 
of the glass, while air is blown into the tube. 
This small opening is made level with the 
rest of the tube, and the glass is bent at the 
regulation angle about two inches above this 
opening. This is then placed in the rubber 
stopper so that the hole in the glass tube and 
that cut in the stopper will coincide. An 
exit tube for the escape of the liquid is made 
as usual, and the tubes and stopper placed in 
the neck of the wash-bottle in such a way 
that, when air is blown in, it passes through 
the side hole in the stopper, down the wedge- 
shaped groove, and forces the liquid up the 
exit tube. A very slight rotation of the inlet 
tube, after the liquid has begun to flow, will 
close the valve, and the pressure of the 
enclosed air will maintain the stream, which 
can instantly be stopped by reversing the 
rotation. If the apparatus is well made, the 
angle of rotation of the inlet tube is very 
slight — not over twenty degrees. I have had 
this apparatus in use for several months, and 
find that it does not get out of order, is much 
easier to handle, and saves more labor in the 
washing of precipitates than any other form 
of wash-bottle. The inlet tube is so small 
that no appreciable evaporation of ammonia 
occurs, nor does a rise in the temperature 
of the laboratory result in an undesirable 
washing of the working benches. — David 
H. Browne. 
[Original in Popular Science Mwe.] 
ORDINARY ACTIONS OF OXYGEN. 
BY GEORGE L. BURDITT. 
In the year 1774, philosophers all over th< civil- 
ized world were astonished by Dr. Priestley's < iscov- 
ery of oxygen. It has rightly been called th t most 
important discovery of that century, and r vailed 
Newton's discovery of gravitation in the pre eding 
century. Besides forming an epoch in the pi jgress 
of learning, it put an end to old chemical th ories, 
and at the same time laid the foundation of n odern 
chemistry, furnishing a key to many of Niture's 
secrets. But, while Newton's discovery is .insur- 
passed in grandeur, Priestley's is more closely con- 
nected with earthly affairs. 
Oxygen is the most abundant of all the elements. 
It composes at least one-third of the earth, one- 
fifth of the atmosphere, and eight-ninths by ^veight 
of all the water on the globe. It is also .1 very 
important constituent of all minerals, anima.s, and 
vegetables. Oxygen may be prepared in a \ariety 
of ways. One way is to heat mercuric oxide in a 
tube or retort. Mercury is soon condensed in the 
coolest part of the retort, and a gas is liberated, 
which may be collected over water : 2HgO=2llg-|-02. 
It was by this method that Dr. Priestley discovered 
the gas. A supply of very pure ox^'gen may be 
obtained by the action of heat upon potassic chlo- 
rate. A flask may be used to hold the chlorate, and 
the gas may be collected in jars over water. When 
the quantity of chlorate is large, the heat required 
is apt to soften the glass of the flask in which the 
chlorate is decomposed. It has been found that 
metallic oxides, if mixed in a fine powder with the 
pulverized chlorate in the proper proportions, cause 
the expulsion of the gas at a much lower tempera- 
ture, although such oxides do not appear to have 
experienced any change during the operation. 
Black oxide of copper or oxide of manganese are 
the oxides generally used, but the resulting oxygen 
always contains traces of chlorine. These are the 
simplest ways of getting oxygen for experiments, 
although many others exist. 
Oxygen is a colorless, tasteless, and scentless 
gas, a little heavier than air, (specific gravity 
1. 1056), and only slightly soluble in water. It was 
first condensed to a liquid by Pictet and Cailletet, 
but the operation was quite diflicult. It refracts 
light the least of any known substance. At ordi- 
nary temperatures it possesses weak magnetic prop- 
erties, but its susceptibility to magnetization is 
diminished, and sometimes disappears temporarily, 
at 325°. Oxygen has a strong attraction for other 
elements, excepting fluorine, and enters into combi- 
nation with them, forming a great variety of com- 
pounds. With some elements it forms gases ; with 
others, liquids ; with others, solids. Some of these 
compounds give up their oxygen with great ease, 
while others do not. With one set of substances it 
forms neutral compounds; with others, alkalies; 
with still others, acids. With some elements it 
forms nourishing food ; with others, deadly poisons. 
Mingled with one gas, nitrogen, it forms the air we 
breathe ; combined with another gas, hydrogen, it 
forms the water we drink. It is necessary to the 
support of all animal life, and hence was called by 
