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SCIENCE. 



ter bearing date 30th January, iS8o, spoke of " a novel 

 and interesting result," referring, probably, to the above- 

 mentioned photograph. Since then, Dr. Hugginshas 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 characte ristic lines of wate. 



Prof. J. Trowbridge has recently studied the earth as a 

 conductor of electricity and details somejintcresting experi- 

 ments, and advances some bold speculations and prophe- 

 cies in the Ameiican 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 , ,'„,, 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. 



M. Scheurer-Kestner in a note to the Academic 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, ivoVe 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. 



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 osmicacid as 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 \)/ 2 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. 



