-
Title
-
Scientific. Science Notes
-
Description
-
Australasian (Melbourne, Vic. : 1864 - 1946), Saturday 25 February 1899, page 29
SCIENTIFIC.
SCIENCE NOTES.
By PHYSICUS.
BACILLUS OF SMALL-POX.
The rapid advance of the germ theory of disease, which iB a thing of the last few years only, might make ordinary people imagine that physicians had at any rate dis
covered the forms to which each disease is
due, and so are on tbe right road to its successful treatment. This is, however, not the case, and small-pox is an instance of a disease in which the specific bacteria which cause it have long eluded recognition. The method employed in such a case is to make what is known as pure cultures of the various organisms found, and then to experiment on animals with them. In a bacteriological laboratory bacteria are grown on jelly or broth or something of that kind in small glass tubes, and the task of growing a pure culture, that is a culture which con
tains one and only one kind of bacterium, is a long and tedious one. The germs of bacteria, as well as the bacteria themselves, swarm everywhere, in air, earth, and sea. Anything of an animal or vegetable nature will decay, and the decay is in every-day life not an easy thing to prevent. This decay is in nearly every instance due to the fact that bacteria are swarming in the dead material, and reducing it to a series of simpler chemical compounds, which in their turn are suitable food for the higher plants. The difficulty the bacteriologist has to face is not to get a growth in his tubes of jelly, but to get only the kind he requires. Every article he uses must be sterilised, or devoid of living germs of any kind, and the precautions he habitually employs would seem ludicrously unnecessary to an outsider, but experiment has shown how imperative they are. Then the pure culture has to be used on a large number of animals, and the results carefully noted, so that time slips rapidly on. The material from a small-pox vesicle contains a very large number of different kinds of bacteria, and the claims of each kind have carefully to be considered. 31 r. A. F. S. Kent claims to have discovered the special kind which causes the disease. It is to be hoped that the observations of other workers will confirm his results, for though vaccination is an excellent preventive, still with a remedy derived from pure cultures in use it is , robable that inoculation will be less uncomfortable for those who undergo it than
it now is.
LIGHT-WAVE TELEGHAPHV.
Among the many devices suggested for the transmission of messages to a distance there is none more interesting than the method devised by Professor Carl Zickler; the apparatus required is of a very simple character and fairly portable, and the signals can be given and read with great ease. Moreover, the two main dis
advantage- in ordinary systems of wireless telegraphy are "verc-ome, inasmuch as the signals are ouly transmitted in one definite direction. and, so
only rea<Ti the intended receiver, thus at ori>-e ensuring secrecy and avoiding waste
of power.
The e.-sen'-e of the method consists in the u-e "i—11 the sh rt waves o: ""ultra-violet" light —the -called "phot graphic" waves— instead of the long electromagnetic waves of Marconi's apparatus: and i2> ^ vessel cor.t^.ror.g air instead of a tube of metal tilings. Twelve years ago. Hotz proved that the impact of waves of ultra-violet light increases the conductivity of air. just as Br&niy subsequently found that the imp-act of electric waves increases that of a layer of tilings. Zickier's method therefore requires tor a transmitter merely a powerful source of light, ar.d some means of cutting of the invisible ultra-violet rays, or allowing theru to pass, at pleasure. Glass ab.-orbs these rays completely: consequently the inter: osttion of a thin glass piste cuts thern of; without r-erceptibly weakening the v;-; 1 ie rays.
As the s< ur--e of light— ultra-violet at.: other — a ; •■v-rful electric are is employe:. Th .- r-lacec at the focus of a large mirror. >u- h a- is u-e-t in projecting apparatus for ::.-.«h-.:ghi work, in order to concentrate the rays and send then.1 in any de.-ired dir—tion. At the receiving -ration the rays G:. on a ouartz lens, by which they are i r-iught to a :oci:s. Behind the iens is a glass vessel with a quartz front: into the sides of th:> vessel are sealed two wires, one of wfay-h terminates in a small ball, the other in a polished disc inclined at i'-deg. to the path of the light: the focus oi the iens is on this plate. Both pi ate and ball are faced with platinum.
The wiies are joined to the secondary terminals of an induction coil, in such a way that the p<-u»hed disc- forms the cathode. <.:• negative plate. The distance between ball and disc • - a lit we too great to allow the ark fr m the c-oil to pa.-?: but whenever the beam of uitra-violet light falls oil the disc the s ark once passes, discontinuing a,- soon as the beam is shut off. The operator at the sending -ration has oniy to open and close tne gias? shutter, by meat.- of a nneuniatic arrangement, in order to transmit the signals. The passage of a -; ark in the receiving apparatus mat be detected in several ways: if it be desired to read the signals by ear a telephone is inserted in the secondary circuit of the coil, and a sharp "c-rack" is heard in the telephone at each pas-age of the spark. If. however, it be advisable to print the message on a tape, a relay is used instead of the telephone. When the spars passes the relay closes its local circuit and actuates a Morse ink-writer, ju?t as it doe- in ordinary telegraphy.
The greatest distance to which Professor Zickler has succeeded in transmitting signals by th is method is a little under a mile: but there is no doubt that this can be greatiy inc-reased. The projecting mirror he employed was not very suitable, as the metal of which it is composed does not reriect anything like the- whole of the ultra-violet light which falls upon it. The receiver, too, was judged capable of improvement. The quartz lens employ...i was not large enough to sufficiently concentrate the ravs on to the electrodes. Ziekler found that*a reduction of the pressure of the air inside the receiver was a great advantage: but further im e.-tigaton is neeoed to determine the most suitable air-pressure to employ. Experiments intended to settle these point? are ?ti]I in progress; but the results already obtained show that the processes devised by -Marconi and Preece have to reckon with a dangerous rival.
MKKoSn .)!>](. Kl LKIl LINKS.
At a recent meeting of the Royal Micro-enpic Society, London, the president, Mr. E. M. Nelson, exhibited some ruled, glass plates which had been prepared and presented to the society by Mr. H. J. Gray
ton, of Melbourne. In the measurement of the size of microscopic objects, such as, for instance, blood corpuscles or cells of the yeast plant, a small glass piate with a number of equidistant lines ruled on it is placed in the tube of the microscope in such a position that the lines and the object to be measured can both be clearly seen on looking into the instrument. In an ordinary theodolite, or level, used by surveyors, two crossed wires, wbicb are really spider's web. can be seen similarly, and are used so that by bringing tlie
C. A. BENNETT.
Winner of 1 mile and 3 miles Championships.
W. SHEA,
Winner oi Treble—100 yards, 220 yards, and 440
yards Championships.
crossed wires on any point, its bearing irom the point of observation can be judged. In both the microscoj>e and the theodolite the lines are in the focus of the eye-piece. The mere observation of the ruled lines in the microscope is, however, of itself no guide as to the size of the object to be measured, for not only does the "objective," or collection of lenses, near the object magnify it, but the eye-piece magnifies the ruled lines, and makes them appear further apart than they really are, and these variable factors will be different for
every combination of eye-pieces and objectives, and also for every change in the length of the microscopic tube. \Ve then require some means of measuring the apparent distance of the ruled lines for every combination which we are likely to use. This is attained by having another plate of glass, which is placed on the microscope stage in the position where we usually place an object which we are examining. This second plate, also, has lines ruled on it. and the distance between these is known. In an ordinary carpenter's rule we
have an inch divided into eighths, while draughtsmen and others have still finer scales. These, however, are far too coarse
for microscopic work, and some very astonishing ruling has been done at times. The finest ruling 6ent by Mr. Grayson on tin's occasion contained no fewer than sixty thousand lines to the inch, and another contained two thousand to the millimetre.
These he can exceed. Lines like these are. of course, ruled with a diamond point, ana by a machine constructed for the purpose. It is essential that they should be correctly spaced and sharply cut, without ragged edges. With regard to Mr. Grayson's plates, it is interesting that Mr. Nelson
should say that they are among the best he had ever handled, and that he could congratulate the society on the possession of two accurate plates for the purpose of comparison.
TWO NEW ELEMENTS.
The discover}*, made by M. Henri lleoquerel, that uranium and its compounds possess the property of emitting rays very
similar in character to the Rontgen rays has resulted in a new method of chemical research. Uranium does not stand alone in this respect, and it is now possible to identify the presence of certain substances in a compound by raeanB of their greater or less power of emitting these rays—their "radio-activity" as it is termed. A short time ago a new element—to which the name polonium" is assigned—was discovered by M. and Mme. Curie in the mineral pitchblende. Polonium in many
respects resembles mac, bat ditlerTwT, by possessing the property of radio-activit* in a more marked degree CTen thta uranium. While following up this X
covery, the same investigator, have W« ' led to another. They found tli-.-.t. one 0{!?® mixtures with which they were working contained another radio-aeth substenl This resembles banum-the maallic con stituent of '^eavy epar"-ir , s chemical properties, To partially set.:.- .a; it from accompanying elements ao. utage Was taken of tbe fact that iu chloride is soluble in water but insolubh m alcohol ThiB allowed tbe method of : notional pre', cipitation to be employed, and was found that the radio-activity of mi • ssive small fractions steadily increased, last frac lion having an activity nine » ■ .died times greater than that of uranium This frac ticm was examined spectres. vioally. it proved to contain barium, :■ i. calcium and platinum; but, in add ,on to the spectra of these elements, a Mrcng newline was seen, indicating the presence of the newly-discovered substance, ' which the
investigators appropriately a ;?n the de
signation "radium.'
FORMATION OF PhASTFU > PARIS.
During the holidays some Ponds picked up a few crystals of gypsur. <m the sea cliffs, and as they seemed n . vested in hearing how it came there a 'Vscriptk® 0f the process may not be out m place. The
POLE JUMP CHAMPIONSHIP : J. M'RAE CLEARING 9ft. ilw.
cliffs from Torquay to Spin I'oint are. in the main, formed of clays v. h were laid down on the sea bottom, an-; ere in many places full of the remains fossil shellfish and other animals win- lived in the sea while the waste mater., was being carried down to form the i' . accumulations which have since bet: . levated to form dry land. This sea-b ■;.-<• mud carried with it a certain atnour;! iron which is everywhere present, and tk: ■ iron, which was probably mostly in the :.,nn of iron rust, or oxide, united with the sulphur contained in the bodies of tin i- ad animals and plants which strewed t!r : atom, and tiius formed iron pyrites. N des of this pyrites are very common in? darkercoloured clays, just, in fact. hey are m the deep auriferous leads 01 toria and elsewhere, and where they h ■ originated in the same manner. Now. ■<>« pyrites formed in this way is usuub ry readily acted on by the oxygen of ' dr. so that the brassy-looking sulphide urned into the sulphate of iron, whi<! known in trade as copperas, or green ■'>]. this substance is readily soluble water. and is very ready indeed to un with more
oxygen, so that, being what chemists call ,m unstable compound, we rarely find it m nature. The effect of the union of more
ixvgen is rather a complex one. Most of i he iron is deposited as iron rust or oxide, which is a reddish brown in colour, and <he remainder is left_as another peculiar
•ilphnte of iron, which will not dissolve in water, and which has a yellowish hue.
., the same time some of the sulphuric ■ eid, or oil of vitriol, which was united
ill) the iron is set free. This acid at nee attacks any lime in its neighbour
nd. and turns it into sulphate of lime,
jeh is slightly soluble in water. Gra.,:i] 1 v this sulphate of lime collects—how . not known—and crystallises as gvpsum,
as it is then called by mineralogists, .mite. It is transparent when pure, and its into plates, which can easily be i.itched with a nin, and have a peculiar
-re like horn. When gypsum is found in •jo deposits, as it is in many places, it is
ted to drive off the water which its <tals contain, when it falls to a soft , ito powder, known as plaster of paris.
is. when stirred up in water will, as >st people know, set as a stony mass,
is is due to the fact that it combines ill the water with which it is mixed, and
it does so gradually, and not suddenly, • an he used ^for casting various orna. lit s. or for plastering. It may be inen
iod that the method of formation here vibed is not the only one which nature ■ids. hut is a common one in marly Vs.
-
Date Issued
-
1899-02-25
-
Creator
-
Physicus
-
Publisher
-
The Australasian
-
Links to Trove
-
https://trove.nla.gov.au/newspaper/article/138673219/11316183
-
Location State Territory
-
Victoria
-
Location Town City
-
Melbourne
