Vol. XXV. No. 2.] 
POPULAR SCIENCE NEWS. 
^5 
^hfe l^opular Science I^ews. 
BOSTOX, FEBRU^VBY 1, 1891. 
AUSTFN P. NICHOLS, 8. B EDITOR 
WILLIAM .T. ROLFE, LiTT.D. . . ASSOCIATE Editor 
Just as the January number of the Popular 
Science News was about to be put on the press, 
; a fire occurred iu the printing establishment, whicli 
[ caused a delay of over a week, some of our suli- 
icribers not receiving their copies till the middle 
i of the month. Tlie damage was not large, how- 
j ever, and, if no other misfortune occurs, the pres- 
t ent issue will be mailed at the usual time. Tliis is 
tthe third time in the history of the Xews that fii-e 
has occurred in its oflices; but, fortunately, in all 
I cases there has been little actual loss, although 
much delay and annoyance has been caused the 
[publishers. 
*♦* ■ 
The many friends of our distinguished contrib- 
! utor. Professor Young of I'l-inceton, will be 
pleased to learn that he has been awarded the 
■ Janssen prize for 1890, by the French Academy of 
Sciences, in recognition of his brilliant discoveries 
fin spectroscopy. Professor Young stands iu the 
^ foremost rank among astronomers and solar physi- 
I cists, and it is a matter for congratulation that 
[the prize was not onlj' awarded to an American 
I astronomer, but to one who is so worthy of it in 
fevery respect. 
In another column will be found the report of 
I Dr. Koch regarding the composition and prepara- 
|tion of his IjTnph. Although somewhat unsatis- 
I factory in failing to give the particulars of its 
f manufacture, and containing many incomprehensi- 
( ble statements, — probably due to errors in transla- 
tion and telegraphic transmission,— it gives a fairly 
tgood idea of the nature of the now famous lymph. 
kAs has been surmised, the effective substance 
fseems to be a product of the organisms of 
[tubercle bacilli, and is obtained by extracting it 
Iwith glycerine from a nutritive fluid in which 
I they have been cultivated for a sufflcieat length of 
[time. It is noticeable that Koch has no definite 
explanation to offer, either of the exact chemical 
I nature of the effective ingredient, or the manner 
hi which it exerts its remarkable influence upon 
I tuberculous tissue. In fact, the quantity present 
[hi the undiluted lymph is so minute — a fraction 
Fof one per cent. — that investigations upon these 
I points will be attended with unusual difficulties. 
E After all, perhaps the most interesting and impor- 
I tant part of his report is found in the couckiding 
[sentence, iu which he says that two consumptive 
[patients inoculated three months ago have had 
Ino return of their symptoms, and are apparently 
I cured. Fuller details, by mail, will be awaited 
Iwith interest. 
A WORD of commendation should be given to 
(Dr. Koch for the eminentlj' scientific way iu which 
[his great discovery has been announced to the 
[ world. From the moment of his original com- 
l^munication to the Berlin Medical Congress last 
; summer, when he modestly stated the probability 
of the curability of consumption by this means, a 
I most tremendous pressure has been brought to 
[bear upon him from every side to divulge the 
-secret of the remedy; but, realizing the incom- 
pleteness of his work, and the dangers attending 
the indiscriminate application of such a powerful 
and little understood agent, he steadily continued 
his investigations until his first results were con- 
firmed; and, after a limited but careful experi- 
mental proof of the efficacy of the "lymph,'' he 
has finally made a free gift of his discoverj- to the 
whole woild. To a less high principled man the 
temptation to quackery would have been irre- 
sistible ; as it is, this has been confined to writers 
for the daily press, and, owing to Koch's wise 
silence, they have had little basis of fact for their 
sensational articles, and have been compelled to 
confine themselves almost entirely to the imagina- 
tion. 
But bacteriological science is not only occupied 
HI curing disease, for in destroying the lower 
forms of life it may also prove of great benefit to 
mankind. It is stated that Professor Snow, the 
State Entomologist of Kansas, has successfully 
introduced a contagious disease among the chinch 
bugs which infest the grain fields of that State, by 
placing previously inoculated bugs iu the fields 
among the healthy ones. It is claimed that the 
bugs in these fields were exterminated, and the 
farmers declare that their crops were thus saved 
from destruction. If this method of destroying 
this devastating insect proves successful on a 
large scale, it will be of the greatest economical 
importance — especially as it includes the proba- 
bility of the destruction of other pests by a similar 
method. 
A CORRESPONDENT at Akron, Ohio, sends us an 
account of a sad accident, caused by the light 
dresses of several young ladies accidentally taking 
fire during some Christmas festivities in that citj', 
by which two were fatally, and several others 
seriously burned. The danger arising from the 
high inflammability of light cotton and linen 
clothing has led to manj' attempts to render it 
incombustible by treatuig it with certain chemi- 
cals. Among the best of these is the salt known 
as tungstate of soda ; and, on receipt of our cor- 
respondent's letter, we made some practical ex- 
periments with it. We found that when cloth, 
cotton wool, and similar substances were soaked 
in a strong solution of this salt and dried, tliey 
could be placed in contact with fire without burst- 
ing into flame. The material charred and smoul- 
dered away, but there was no blaze, and the fire 
could be easily and quickly extinguished. The 
appearance of the treated cloth was unaltered, 
and, if necessary, it could be starched and ironed, 
although, of course, washing the cloth would re- 
move the salt. Tungstate of soda is comparatively 
inexpensive, and in cases where there is danger of 
clothing taking fire it can be used in this way to 
great advantage. 
The application of the stereoscopic principle to 
magic lantern pictures, by which they appear to 
stand out from the screen in relief, has been ac- 
complished in a most ingenious manner. As is 
doubtless known to our readers, iu the ordinary 
stereoscope two slightly dissimilar pictures are 
combined into one by means of properly formed 
lenses. In the magic lantern projection two lan- 
terns are used, and the two pictures thrown upon 
the screen so that they will be superposed upon 
each other, as in the familiar dissolving views, the 
only dift'erence being that in one lantern a green 
light is used and in the other a red. These colors 
being complementary to each other, the combined 
images on the screen appear to be of the usual 
white color. But if, now, the spectator places 
before one eye a piece of red glass, and before the 
other a green one, the combined pictures on the 
screen are separated, each eye seeing a difl'erent 
one corresponding to the color of the glass before 
it. But, by a well-known law of vision, the two 
separate and slightly differing images are re-com- 
bined by the eyes, and only one image is perceived, 
but iu relief, the same as when looking through a 
stereoscope. The efli?ct is said to be surprising, 
and the only disadvantage of the method Is that 
when the pictures are shown to a large audience, 
each spectator must be provided with a pair of 
spectacles fitted with glasses of the proper tints. 
We recently noticed in a restaurant that the 
wires from which an incandescent electric light 
was suspended were completely encrusted with 
dead files. The proprietor said that although they 
were constantly removed, they continually gath- 
ered there, contact with the wire apparently prov- 
ing fatal to every fly that touched it. The wings 
of every fly were outspread, as if death had oc- 
curred instantaneously at the moment of reaching 
the wire. It hardlj^ seems possible that a current 
of such low intensity passing through an insulated 
wire could destroy even so small an animal as a 
fly ; but such seems to be the case, and we oft'er 
the suggestion freely to any ingenious inventor 
who may wish to devise a patent electrical fly- 
catcher. 
The persistency of old superstitions is shown 
bj' an item which has been going the rounds of 
the papers, stating that the department of justice 
of Canada has decided to purchase a newly pa- 
tented photographic apparatus, which will enable 
a copy to be taken of the image in the retina of 
the eye of a dead person. This is regarded as 
very important, especiallj' in cases where there is 
no other clue to the pei'petrator of the murder. 
The idea that the retina of a dead person retains 
the image of the last object looked upon is an old 
one, but has no foundation whatever in fact ; and 
the only image that could be photographed under 
such conditions would be the reflection of sur- 
rounding olijects, which would, very likely, include 
tlie operator himself. We hope, for the credit of 
the common sense of our Canadian friends, that 
the statement is an incorrect one. 
Garnier has obtained a chrome blue by melting 
together, in a lined crucible : Potassium chromate, 
48.64 grammes ; fluor-spar, 65.0 grammes ; silica, 
157.0 grammes, 'i'he product is a glass of a fine 
blue, surrounded with a thin layer of metallic 
chromium, which is capable of being detached. 
Red, yellow, and green compounds of chromium 
have hitherto been known, and this last discovery 
completes the scale of colors, and shows that the 
metal well deserves its name. 
ARTIFICIAL RUBIES. 
In our issue for June, 1888, we chronicled the 
success of two French chemists, MM. Fremy and 
Verneuil, in artificially producing rubies pre- 
cisely similar iu color and chemical composition 
to the natural stones. 
On the 10th of last November the same chemists 
announced to the Paris Academy of Science that 
they had succeeded in preparing much finer stones, 
which were of a size sufficiently large to be set in 
jewelry, as shown by certain specimens illustrated 
in Fig. 1. As these rubies are precisely identical 
with the valuable natural stones, it is a delicate 
question as to how they should be valued com- 
mercially, as the only difference between them is 
that analogous to natural ice, and that produced 
by a freezing-machine. 
llie natural ruby is simply crystallized corun- 
dum, or oxide of aluminium (ALjO,), with a trace 
of coloring-matter, probably chromium. The 
