POPULAR SCIENCE NEWS. 
[January, 1890. 
metals lithium, sodium, and potassium, which 
very closely resemble each other in their 
chemical relations, form a group by them- 
selves ; as likewise do the non-metallic ele- 
ments fluorine, chlorine, bromine, and iodine, 
which are distinguished by the ease with 
which they all unite with hydrogen to form 
powerful acids, as well as in many other 
ways. There are seven of these groups, 
besides another one which comprises certain 
metals related to iron and platinum, the place 
of which in the system is not well fixed. 
This remarkable and important principle, 
/ which is called the "periodic law," was first 
pointed out by Newlands, in 1864, but was 
more fully developed and brought into gen- 
eral notice a few years ago by Mendelejefl" 
and Meyer, who are generally credited with its 
discovery. Briefly stated, it may be expressed 
that, The qitantivalence and many other 
chemical characteristics of the elements are 
a function of their atomic weights, and it 
is, undoubtedly, the key to many chemical 
mysteries which at present we cannot well 
understand, and much adcHtional study will 
be necessary before we shall know how to 
use the key properly, and comprehend the 
full significance of the law of nature which is 
dimly hinted to us in this periodic grouping 
of the elementary bodies. 
When the elements are arranged as above 
described in groups and series, we find that 
they are not continuous and unbroken. Many 
blank spaces remain to be filled by elements 
possessing an atomic weight between that of 
their nearest neighbors. It is a striking proof 
of the truth of this theory that, since it was 
first brought forward, some of these vacancies 
have been filled by newly-discovered elements. 
When the original table of groups was drawn 
up, there was a vacancy between the elements 
zinc (65) and arsenic (75), which indicated 
the existence of a trivalent element interme- 
diate in atomic weight between those two 
metals. MendelejefF predicted the discovery 
of this element, and the chemical properties 
which it should possess, and gave it the pro- 
visional name of ekaluminium. Shortly 
afterwards, the metal gallium was discov- 
ered, possessing the predicted properties, 
and having the intermediate atomic weight 
of 69.8. Another example is afforded by 
the metal scandium, which agrees closely in 
its properties and atomic weight (44) with 
an element intermediate between calcium 
and titanium, whose existence was predicted 
by Mendelejefl", under the provisional name 
of ekabor. 
To what further discoveries this wonderful 
law may lead, it is impossible to say, but it 
undoubtedly indicates a closer connection 
"between what have been considered as defi- 
nite and distinct forms of matter, than has 
hitherto been supposed. We cannot over- 
look the hint of an inorganic evolution of the 
difltrent forms of matter from one primordial 
substance, analogous to the difterentiation of 
plants and animals from simpler and lower 
forms of life, now so generally accepted by 
biologists. But, whatever may have been the 
conditions governing the existence and mani- 
festations of matter in the early ages of our 
universe, the impossibilit}' of a change from 
one form of matter to another at the present 
time and under the existing conditions, seems 
almost certain. Not a single fact is known 
which leads us to suppose that it is possible 
for the chemist to change hydrogen into oxy- 
gen, for instance, or mercury into gold. 
But, judging from the previous achievements 
of scientific research, we are on the verge of 
some wonderful and revolutionary discoveries, 
which, to say the least, will profoundly mod- 
ify our present views in regard to the con- 
stitution of matter, and the laws governing 
the phenomena which it exhibits. 
«♦> 
SCIENTIFIC RECREATIONS. 
A VERY pretty experiment in inertia can 
be performed with a dice box and two dice, 
held in the hand as shown in the engraving. 
It is required to toss the two dice into the 
box, one after the other. The problem at 
first sight appears ridiculously simple, and so 
it is for the first die, but it will be found 
almost impossible to toss the second one into 
the box without throwing out the one alreadv 
diflicult to move the box directly under the 
second die, so that it shall fall into it without 
throwing out the first one. Like all experi- 
ments of this sort, a little practice is necessary 
to do it successfully, but the trick is soon 
learnt, and is an amusing one in itself, as well 
as an illustration of the fact that, owing to 
the principle of inertia, a body does not 
commence to fall at the exact instant that its 
support is withdrawn. 
The second illustration shows very plainly 
the proper way of bending a glass tube — a 
very simple matter, but one in which chemi- 
cal amateurs often come to grief. The whole 
secret is to heat a considerable portion of the 
tube by moving it back and forth lengthwise 
in the flame, at the same time slowlv revolv- 
ing it between the fingers. When the tube is 
thoroughly and uniformly softened for a space 
there by the same movement. It can, how- 
ever, be performed as follows : After tossing 
the first die into the box, hold the second one 
with the fingers so that it shall be somewhat 
higher than the bottom of the box and the 
die within it. Then give a quick downward 
movement with the hand, at the same instant 
letting go of the die held in the fingers ; 
the latter will not move quite as (juickly as 
the hand and dice box, and it will not be 
of about two inches, remove it from the 
flame, and bend it into the desired curve. 
Take plenty of time, as the glass will not 
harden immediately. In the engraving, a 
spirit lamp is represented, but an ordinary 
gas burner gives a broad flame of just the 
right shape for heating the tube, which 
should be held in the upper part of it, where 
it is hottest. A dense coating of soot, or 
carbon, will be deposited upon the glass by 
the lamp flame, but it will do no harm, and 
can be easily wiped ofl' after the tube has 
cooled. If it is desired to draw the tube out 
to a point, heat it in the same waj , and pull 
gently but firmly, with both hands. If a long, 
slender point is desired, the tube must be 
removed from the flame before drawing out ; 
but to make a short, blunt point, heat the 
glass till it is quite soft, and draw out slowly 
without removing it from the flame. 
The accompanying engravings are repro- 
duced from La Nature. 
Native Zinc. — In the laboratory of the State 
Mining Bureau in San Francisco a discovery was 
made recently which is highly prized. In working 
a specimen of sulphide or blende ore sent from a 
mine in Shasta County, Cal., a small piece of 
native metallic zinc was secured. This is the first 
piece of the character named ever known to have 
been secured in this country. Late works on met- 
allurgy note the existence in the mines of Victoria, 
Australia, of the only native metallic zinc known. 
The Mining Bureau will endeavor to secure other 
specimens from Shasta County. 
