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SCIENCE. 
M. Scheurer-Kestner in a note to the Acaddmic des 
Sciences, qualifies a previous statement that sulphuric acid 
attacks platinum, by new experiments. Absolutely pure 
sulphuric acid does not attack platinum, but if there be ever 
so small a content of nitrous acid, a very appreciable quan- 
tity of the vessel is dissolved, ,^{,55 being enough for the 
purpose. In one of his experiments, on 60 grams of sul- 
phuric acid, two milligrams of platinum were dissolved. 
This fact should be verified by manufacturers of concen- 
centrated sulphuric acid. 
ter bearing date 30th January, 1880, spoke of “ a novel 
and interesting result,” referring, probably, to the above- 
mentioned photograph. Since then, Dr. Huggins has taken 
a large number of photographs of the spectra of different 
flames, but only presents one (that of hydrogen) to the Roy- 
al Society. We regret this, both because of the loss to our 
general stock of science, in this unnecessary detention of 
the spectrum of carbon and its compounds, and because 
of the imminent probability of a repetition of these dis- 
agreeable questions of priority, as, on this side of the water 
(to the writer’s knowledge), this particular subject is being 
eagerly studied under unique conditions. 
The experiment of Dr. Huggins consists of first burning 
hydrogen per se in atmospheric oxygen, and then a mixture 
of oxygen with hydrogen in air. He finds the two spectra 
identical. For purposes of comparison, he very ingenious- 
ly photographs them on the same plate, in rapid succession, 
using the upper half of his spectroscope slit for the first, 
and the lower half for the second impression. As all the 
lines of both spectra fit each other exactly, without excess, 
it is evident that either represents the spectrum of water. 
The article referred to contains a partial spectrum, giving 
the charade ristic lines of wate. 
Prof. J. Trowbridge has recently studied the earth as a 
conductor of electricity and details some interesting experi- 
ments, and advances some bold speculations and prophe- 
cies in the American “Journal of Science for August. In all 
the telephone circuits between Boston and Cambridge for 
a distance of about four miles, the ticking of the Observa- 
tory clock could be heard when transmitting time signals. 
This was attributed to the proximity of the telephone circuit 
wires to the time wires of the Observatory. Mathematical 
considerations, however, (Maxwell’s Electricity and Mag- 
netism, Vol. II., p. 209), will convince one that with tele- 
phones of the resistance usually employed, no inductive 
effect will be perceived between wires which run parallel 
to each other a foot apart for the distance of thirty or forty 
feet, even if ten-quart Bunsen cells be used. The transmis- 
sion of these time signals is evidently not due to induction, 
but to tapping the earth, so to speak, at points which are 
not in the same potential. Running a wiie five or six hun- 
dred feet long to ground at both ends, and putting a tele- 
phone in circuit, the ticking was distinctly heard when an 
exploration was made in an open field an eighth of a mile 
from the Observatory ; yet the same wire, under similar con- 
ditions, gave no sound when one mile away from the central 
line between the Observatory and the Boston office. With 
the boldness of a Gallileo, Professor Trowbridge deduces 
thence the theoretical possibility of telegraphing across the 
Atlantic without a cable. He says: “Powerful dynamo- 
electric machines could be placed at some point in Nova 
Scotia, having one end of their circuit grounded near them 
and the other end grounded in Florida, the conducting 
wire consisting of a wire of great conductivity and carefully 
insulated from the earth, except at the two grounds. By 
exploring the coast of France, two points on two surface 
lines not at the same potential could be found ; and by 
means of a telephone of low resistance, the Morse signals 
sent from Nova Scotia to Florida could be heard in France. 
Theoretically this is possible, but practically, with the light 
of our present knowledge, the expenditure of energy on the 
dynamo-electric engine would seem to be enormous.” 
A very curious observation has been made by M. J. Jans- 
sen of a remarkable inversion in a photographic image by 
exposure during different times. It passed from negative 
to positive with an intermediary neutral, invisible period. 
After a first exposure of ygVu of a second a negative can be 
developed, a little longer exposure would dull the sharp- 
ness of the image ; then there soon arrives a point where 
the negative disappears entirely. By a still longer expos- 
ure a new phase occurs, a positive image starts out from 
the plate, with lights and shadows just the reverse of the 
first and as sharply defined. By allowing further action of 
the light a second neutral condition occurs. M. Janssen 
does not say by what state this is followed . — Moniteur Sci. 
Mr. Albert Levy finds considerable variation in theammon- 
iacal contents of rain waters collected in the different quarters 
of Paris, but the annual means are identical. The per cent- 
ages diminish from one month to the next, in passing from 
the cold to the hot season. The minimum at all stations 
was for the month of July, when there was present .93 of a 
milligram of nitrogen, against 1.35 in January. The potable 
waters of Paris are affected in exactly the same way. The 
reverse, however, is the case with the ammonia of the air 
which is most abundant in the hot season . — Moniteur Scien- 
tifique , Aug. 
The organisms described by Pasteur as the origin of 
epidemics and contagious disease, are so minute and few 
compared with the multiplying swarms of bacteria, etc., 
pervading all generating solutions, that it becomes neces- 
sary to provide a means of eliminating the masses of infu- 
soria from solutions to be studied under the microscope. 
These microzoa haunt even the clearest drinking water at 
times, and it becomes highly important to easily determine 
their presence. M. Certes (Proceedings Acad, des Sciences), 
suggests the use of osmicacidas a sure means of killing 
them without destroying their tissues. He dips a glass rod 
into the solution to be examined and then into a i]/ z per 
cent, solution of the acid ; washing this in a narrow test 
tube of distilled water, it is easy to collect what is necessary 
for examination. There are certain precautions to be taken 
as to cleanliness and time of immersion. By the use of a 
mixture of Paris violet in diluted glycerine, he finds it pos- 
sible by uniform difference of tint, to easily distinguish 
cellulose, amylaceous matter and the vibrating cilia. 
M. De Lesseps, as an argument against the quarantine 
system, read a letter to the French Academy of Science, 
from the engineer in charge of the preparatory work of the 
interoceanic canal, informing him that a number of persons 
had disembarked at the isthmus while sick of yellow fever, 
without having propagated the disease among the workmen. 
Following this communication of M. De Lesseps, M. 
Bouley said he could not allow the inference from such 
remarks to pass unchallenged. Admitting that what M. 
De Lesseps said was true, that quarantines are a constant 
inconvenience to commercial and maritime relations, yet this 
injury is in the highest degree compensated for by the 
guarantees given to the public health. Since the inter- 
national sanitary police has been watching over Egypt, and 
preserving it from the invasion of cholera by strict quaran- 
tine, this disease had come to be less feared in Europe. It 
is by quarantine alone we shelter ourselves from those dis- 
eases which vessels so easily carry with them, particularly 
the yellow fever to which M. De Lesseps refers. The 
atmospheric conditions which he says render quarantines 
nugatory, cannot contribute to the propagation of epidem- 
ics, unless those who are attacked are allowed to land from 
the vessels which contain the germs. But these germs are 
not intangible exhalations, subtile vapors, effluvia which 
have a property of fatal expansion, against which we can do 
nothing. Quite the contrary is true. Thanks to the re- 
searches of experimental science, the principle of contagion 
is no longer unknown ; it has taken body and can be studied 
and followed in its manifestations. But even before this 
accession to our knowledge, practice, inspired by observa- 
tion, had proved that strict surveillance of men and things 
coming from suspected countries would prevent the spread- 
ing of the germs. This is the province of the quarantine 
and by it alone can it be done. It is, then, necessary to 
maintain it in spite of the convenience to commercial and 
maritime relations. Otto A. Moses, 
