The sun., 1912-07-14

tho proximity of lamp rost on the street
or estimate the size Of an object brilliantly
lighted, such ~ a lamp on table. 10y walk
ing around it"
II you were shark" in chemistry or
physics at school YOU may remember the
descriptio of seenium IA non met allie
element. tho hy-product from the manu-
facture of sulphuric acid from iron pyrites
in final crystalline from opaque to light
and Of a duh gray color was discovered by
Berzelius in 1877" Bcrzclius called the
element after the Greek word for moon
selene
No one had any use FOR sclonhim or
cared n snap about il until in ;S73 Will
, loughhy Smith discovered tha. when an
electric current was passing through a
bar Of crystalline selen;,im its resistance
was less when exposed to the action Of
bright light than when the light was
feeble
/ That was curious and started all sorts
of experiments to find out why il WAS So
and TO sec what use could be made Of il
The nearest to finding out why is nothing
hut good guess as stated by Prof Sever
inghaus. that the three variet les in the
metal. normally in perfect balance. are
upset bv light rays and let the electric
current through. But the other side Of the
discovery uses that could be made of se-
lenium' 5 peculiar quality have been mani
fold, important and as vet unexhausted
Of course the more interesting Of these
uses are those which have commercial
value and attention will be given chiefly
to such. but before they are spoken OF
pention may la made Of a highly pic.
turcsque and dramatic experiment per.
formed by ". j. Hammer. consulting
electrical engineer Of New York Mr.
Hammer told about it al his home, Is:
West Rorty-sixth street.
II was showing an audience some of tn,
things that this property Of eeenium cna
hlcs one to do" said Mr. Hammer. "Anc
] had arranged a light TO pass through al
aperture and strike a selenum cell. Thi
made an electric circuit and c,rren
formed. l soon got it adjusted so nicely
that by simply lifting my hand before
the light aperture | could stop the elect ri
current, my hand cutting of the ligh
from the cell and the sclenium becominI
az once non-conductor.
"The dramatic side of the thing lay II
this: had only TO introduce relays I,
make my tiny electric current control tn
mightiest current we know driving tn
biggest dynamos and operating. We vii
say, all the machinery Of big city. Thel
by the simple lifting or dropping Of m,
hand all the wheels of the city would hav
stopped or begun spinning"
Why did Berzelils name his new elemen
after the moon il may reasonably b.
asked? Well. the scientist perhaps wa
empty minded or imaginative at tn
moment in 1917 when he took the matte
under adviscment, At any rate the cart
and the moon wcrc close together "A bi
unusually SO, and so he called the ne,
thing after tho Greek word for moon
More reasonable was the added fact tha
, selenium Possessed properties strikingl
similar 10 those of tellurium, which wa
, named from tho Latin word tellus, tn
earth.
S"lenium is rather heavy. Its spccf
: gravity when crystali2fd is Ass, whc
is about half ar heavy as iron. II ha
!, Chara cterstics similar to those of phos
phorus and sulphur as well as telurlun
IT has no taste and ordinarily it has n
= small. hut. n the new tnc-c!opTdi
/ Britannica feelingly observes it burn
, with blue fame when heated in the al