92 
POPULAR SCIENCE NEWS. 
[June, 1S90. 
The Constellations.— The positions given liold 
good for latitudes differing not many degrees from 
40" north, and for lo P. M. on June i, 9 P. M. on 
June 15, and S P. M. on June 30. Bootes is in tlie 
zenith. Libra is on the southern meridian, about 
halfway up, and Scorpius is a little below and to the 
east of Libra. Sagittarius is on the southeast hori- 
zon. Corona Borealis is near the zenith, to the 
southeast. Hercules is high up in the east, and 
Aquila is below it. Lyra is about halfway from 
horizon to zenith, a little north of east, and Cygnus 
is below Lyra, in the northeast. The bright stars 
in Ihe head of Draco are in the northeast, high up. 
Ursa Minor is on the meridian, mainly between the 
pole and the zenith. Cepheus is a little below and 
to the right of the pole star, and Cassiopeia is near 
the horizon, a little east of north. Auriga is just 
setting, about 20° west of the north point. Ursa 
Major is in the northwest, high up. Gemini is 
setting, a little north of west; Cancer is a little 
above, to the left; Leo is above Cancer, and nearly 
due west. Virgo is in the southwest, about halfway 
up. 
Lake Forest, III., May 3, 1890. 
M. 
Correspoijdeiice. 
Ilrief cflmmvvi'ations upon suhjects of scientific interest 
will he weicnmed fri'm aity tf/t(irter. Tlie editors do not neces- 
Sftrily indorse all views and statfrnents presented by their 
correspondents. 
SAFETY IN PREPARING OXYGEN. 
Editor of Popular Science News: 
An editorial in the current number of the Popu- 
lar Science News notices a disastrous accident 
that occurred while oxygen was being generated in 
a public school at Lexington, Illinois. As I am 
deeply interested in the subject of science teaching 
in public schools, I sincerely regret both the fact of 
such accidents and the publication of them, unac- 
companied by a statement of such precautions as 
will help to prevent their recurrence. 
During the past eight years, each one of more 
than one thousand students — mostly girls — has gen- 
erated oxygen at least eight or ten times in our 
laboratory here, without a single explosion occur- 
ring. Therefore, I hope you may find place in your 
valuable journal for a brief account of how we avoid 
such accidents, in order that all may be encouraged 
in performing such simple school experiments as 
may serve to stimulate the minds of the young with 
facts that enrich intelligence and excite mental 
activity. • 
The explosions that occur while generating oxy- 
gen are usually attributed to charcoal dust as an 
adulteration in the manganic oxide; but a far more 
common source of danger consists in the fact that 
careless druggists sometimes sell "black antimony" 
(antimonic sulphide) for manganic oxide — the two 
resembling each other in being black and pulveru- 
lent. "Black antimony" and potassium chlorate 
are constituents of some exceedingly powerful ex- 
plosives, and any attempt to generate oxygen from 
such a mixture proves disastrous— as the writer 
knows by personal experience. 
In order to avoid the possibility of such accidents, 
a small quantity of the oxygen mixture should be 
heated in an open receptacle — a common tin tea- 
spoon answers the purpose well. If either anti- 
monic sulphide or charcoal be present in dangerous 
proportions, the violent combustion resulting will 
manifest that fact without doing any harm. If all 
materials for generating oxygen be thus tested 
before they are put upon the laboratory shelves, 
there need be no fear of such sad disasters as that at 
Lexington ; for, with such precautions, generating 
oxygen is far less dangerous than the necessary 
daily experiment of lighting an ordinary "coal- 
oil" lamp. Very truly yours, 
Geo. R. Kleeherger. 
State Normal School. San Jose, California, 
March 24, 1S90. 
[Note by the Editor. — Another cause of explo- 
sions in preparing oxygen gas, is from the delivery- 
tube becoming stopped up by particles of solid 
matter carried over mechanically. We have even 
known a small lead tube to fuse from the heat of 
the escaping gas. The precaution of using large- 
sized delivery-tubes is obvious.] 
"THE EVOLUTION CLUB" OF CHICAGO. 
Editor of Popular Science News: 
A FEW gentlemen in this city, believing that 
science can be advanced in a manner at once socia- 
ble and pleasant, recently issued a call for a meeting 
of scientific men to form a club with the above 
name. On the first evening there were forty-two 
present, and twenty more will attend the next meet- 
ing. The plan of the exercises is somewhat novel. 
We meet at one of our best hotels, the Tremont 
House, at 6 P. M., and at 6.30 P. M. sit down to an 
excellent dinner, after which short papers are read 
and addresses made until 9 30 P. M., when, without 
any parley, the president declares the meeting ad- 
journed. An executive committee of five members 
manages all details. It appoints a new president 
for each meeting, selects the subject for considera- 
tion, and chooses one or two persons to lead in the 
discussion. The leaders are allowed fifteen minutes, 
but subsequent speakers only eight minutes. This 
insures condensed and terse statements, and, es- 
pecially with such comfort as a cigar can give to 
those who smoke, prevents the exercises from 
assuming a wearisome and monotonous character. 
The meetings are held every alternate Wednesday 
evening, and the expense is $1.00 for each dinner, 
and $1.00 per year to cover the cost of stationery 
and printing. The name of the club was chosen 
because it may with propriety include every subject 
of living interest at the present time, and because it 
is well adapted to influence, in some degree at least, 
the selection of members. The society is not de- 
signed for direct missionary work. Indeed, it 
would seem cruel to inveigle a heathen into such a 
society, and then, fifty against one, maul him to 
mummy. The design is rather to so cultivate the 
members, by mutual aid, that one may overcome a 
thousand. H. D. Garrison. 
Chicago, III. 
QUESTIONS AND ANSWERS. 
Letters of inquiry should enclose a two-cent 
stamp, as well as the name and address of the 
writer, which will not be published. 
Questions regarding the treatment of diseases 
cannot be answered in this column. 
Subscriber, Allegheny, Pa — In dissolving potash 
lye in water, the temperature of the liquid nearly 
reaches the boiling-point. What is the cause of the 
heat ? 
Answer. — The caustic potash unites chemically 
with the water, and, as in all chemical reactions 
where atoms combine with each other, a definite 
amount of heat is generated. 
B. S. T., Michigan. — What becomes of the energy 
of running water after it reaches the ocean.' 
Answer. — The energy radiated from the sun raises 
the water from the ocean to the higher levels of the 
land. A mass of water at any distance above the 
se.a-level repre-sents so much potential energy. As 
the water falls back to the ocean-level, it gives out 
this energy, which is finally converted into heat by 
friction, either directly, or by an intermediate trans- 
formation into work or power, as illustrated in every 
water-mill. 
B. T. H., Kansas. — A travelling showman in this 
vicinity has been amusing his audiences by lightinL; 
cigars, gunpowder, etc., with an icicle. There is. 
apparently, no deception, and perhaps you can ex- 
plain how it is done. 
Answer. — It was undoubtedly accomplished by the 
aid of a small bit of metallic potassium or sodium, 
concealed in the substance to be ignited. These 
metals, when moistened, decompose the water with 
great violence, developing so much heat that the 
escaping hydrogen gas spontaneously ignites. These 
metals are not quite safe to handle, and had better 
be let alone by inexperienced persons. Serious 
burns and explosions have resulted from their care- 
less'use. 
J. M. N., Oregon. — What is the longest possible 
duration of a total solar eclipse.'' 
Answer. — About four minutes is the greatest dura- 
tion of totality, and it is usually much less than this. 
The greatest width of country which such an eclipsr 
can cover is 173 miles. Laughable mistakes havt- 
often been m.ade by unscientific novelists, who have 
introduced solar eclipses into their stories, in which 
the phenomena described varied widely from thosi' 
possible under astronomical laws. 
E. N. S., New liedford. — You will probably find 
citric acid, which is soUl by all druggists, a good 
substitute for lemon juice in removing fruit stains 
from the hands. It is the same acid that occurs in 
the fruit itself. 
LITERARY NOTES. 
A Satchel Guide for the Vacation Tourist in Europe. 
Second edition for 1S90. Houghton, Milllin \ 
Co., Boston. $1.50. 
This favorite guide-book, now in its nineteentli 
year, has been carefully revised for the present sea- 
son, it covers tl>e ordinary range of summer travel 
in the British Isles and on the continent, and is 
eminently sensible and practical in the information 
and advice it gives. It is compact and yet compre- 
hensive ; full enough for the vacation tourist, but 
not bewildering and tantalizing him with a loni^ 
list of minor objects which it is better to ignoiv 
than to try.to see in a brief trip. It is particularly 
valuable for its minute and honest account of hotels 
— not only first-class, but those less expensive. 
Indeed, it seems to be the only book of its class 
which is suited lo the wants of thrifty travellers as 
well as of those who are not obliged to count the 
cost of a foreign tour. The maps are also much the 
best to be found in any European guide-book pub- 
lished on this side of the ocean. 
Foods for the Fat: a Treatise on Corpulency and a 
Dietary for its Cure, by N. E. Davies, of the , 
Royal College of Surgeons, England. Lippiucott | 
Co., Philadelphia. 75 cents. ' 
This little book contains a concise discussion of 
corpulency and its general treatment, according to 
the latest views on the subject; followed by over 
four hundred receipts for dishes suited to pcr.sons , 
who desire to reduce their weight. It might have | 
been entitled "A Cook-Book for the Corpulent," \ 
and in this respect it is, so far as we are aware, a 
new departure in "anti-fat" literature. The culi- 
nary receipts are English, but the great majority of 
them are none the less available in American fami- 
lies. ■ The book has, moreover, been adapted to 
Yankee tastes and wants by Dr. Chas. W. Cireene. 
As he remarks in his introduction, "very many of 
the recipes will be found extremely useful to the 
householder, apart from their special value in the 
treatment of obesity." Not a few of them will be 
new to our cooks. 
Essentials of Forensic Medicine, Toxicology, and Hy- 
giene, by C. E. Armand Semple. Published by 
W. B. Saunders, 913 Walnut street, Philadelphia. 
Nearly ever^' phyiiician must, at some time, be 
called upon to testify in regard to matters connected 
with his profession, or, in other w.ays, to have deal- 
ings with courts and lawyers. This little work 
gives many useful flints for such cases, and may be 
the means of saving much trouble ami anno_)'ance. 
The pages on hygiene, and the directions for the 
chemical detection of poisons, are a valuable addi- 
tion to the work. 
Chemistry : Inorganic and Organic, by Charles L. 
Bloxam. Seventh edition. Revised and edited by 
John M. Thomson and Arthur G. liloxam. Pub- 
lished by P. Blakiston, Son & Co., Philadelphia. 
