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glass. Any two of these form an opaque combination—that is It seems probable, from a discussion of former observations, to say, the first glass stops all the rays which could pass the that the polarisation of the sky is al:ogether changed during second. and the second stops all that pass the first. But a green totality, and that instead of being radial to the sun as at other and a blue glass do not form an opaque combination, but pass times, its plane is perpendicular, or nearly perpendicular, to the the green rays. If we place the red, the green, and the violet horizon. This appears at all events to be the case over a very glasses in a row close to each other, with the green in the centre, large area about the eclipsed sun. place a piece of yellow glass so as to overlap the junction be In passing along a parellel to the horizon through the sun's tween the red and green glasses, and a piece of blue glass to centre, we should expect to find, at some little distance from the overlap the junction between the green and violet glasses, and limb, the pure atmospheric polarisation unaffected by any comarrange the combination so that white light can pass through it, ponent due to the corona. it will be seen that the yellow glass passes the red and green rays, At such a point an observer using a Savart might therefore and the blue glass passes the green and violet rays; and that the expect to find the bands disappear at an angle of 45° to the only effect of the yellow and blue glasses is to deepen the colours horizon. Having carefully turned out all trace of the bands upon when the light passes through them.

the centre of his field, let him now pass onward towards the sun's Darrock, Falkirk, Sept. 23

JOHN AITKEN limb (directing his attention all the time to the centre of his field

only), when he there perceives the first trace of bands. He will know

that the plane of polarisation has changed. If, on going back. Anthropology and M. Comte

wards, the bands disappear again, while in passing onwards they PERHAPS you will allow me to state that your report of my continue to increase, he will know that that change is due to a paper “On the Anthropology of Auguste Comte," read before component introduced by the corona ; and he will be able to the British Association at Edinburgh, is wrong in two essential estimate the distance from the moon's limb at which such a comparticulars. First, I did not attempt to expound the views of ponent first became visible. M. Comte according to the principles laid down by Mr. Darwin.”

I feel disposed to think that by this method he will be able to Comte's views on man and his relation to the animal kingdom trace the corona further than he could by the unaided eye ; for it were published upwards of twenty years ago ; Mr. Darwin's re- will be somewhat equivalent to making the corona shine upon a cently. Second, I did not “maintain that Auguste Comte's perfectly black back ground of sky; and much more than equiva. worship of humanity would be the great doctrine of the future.”

lent to accomplishing this with a Nicol only, for the Savart will I may, and do believe this, but I made no reference to it what detect less than one-eighth of the polarisation detectable by the ever in the paper which you have so correctly mis-reported. Nicol. The Positive religion was not the subject of discussion, and I The visible outer border of the corona is where our eye first limited myself to what my paper implied. J. KAINES

distinguishes a difference between 3, Osborne Road, Stroud Green Lane, N., Sept. 22

The light of the sky

and A Plane's ___?

The light of the sky + the light of the corona, IT is perhaps answering somewhat at cross purposes, but while by this method the visible outer edge of the corona will would not the word aspect meet Mr. Wilson's requirements? In

be where we first distinguish a difference between an area of no reference to those important planes of every-day life, garden polarisation and polarisation due to the corona. walls or house fronts, its use is well established; and there would

In using a Savart with a large field, the central portion of the be no violence to either custom or language in applying it to telescope a plate of glass with a small circle etched upon it corre

field might well be marked by fixing in the common focus of the geometry.


sponding say to 8' or 10' of diameter in the field of view. [Another correspondent suggests the term "slope.”—ED.}




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Meteorological Phenomenon

A Rare Moth AMONGST some old memoranda I find the following, which I A FINE specimen of the rare moth Deiopria pulchella (crimson copy verbatim :

JOSEPH JOHN MURPHY speckled footman) was captured by R. Beck on the Moors near Old Forge, Dunmurry, Co. Antrim, Sept. 18

Scarborough on the ith inst. Could any of the readers of Monkstown, near Dublin, about 3.10 P.M. 25th of July, Nature inform me whether it has ever been taken so far north 1858, saw, about opposite the an appearance like


W. E. Waller the rainbow, but horizontal, and extending along a few

Oliver's Mount School, Scarborough, Sept. 22 degrees of the horizon. The red above the sea horizon, and the green below. I could not make out beyond

Meteorology in America the green, but this might be because the blue was blended with The writer of the article on this subject may be interested in the colour of the sea. As I did not see it commence, I cannot hearing that a meteorograph, similar in some respects to that say how long it lasted. It faded gradually but rapidly, without invented by Prof. Hough, was sent to the International Exhi. any other change in the sky that I saw. The day was alternate bition just closed in London. It was invented and constructed sunshine and heavy showers; the sun was shining at the time. in Sweden, and one similar is said to have been performing satis

“ This note has been made within half an hour after its disap- factorily for nearly three years. In the Swedish, as in the pearance."

American instrument, the height of the mercury in the barometer,

and the wet and dry thermometers, is felt by steel wires descend. Lunar Rainbow

ing the tubes ; but in the Swedish instrument the levers to which A VERY perfect lunar rainbow was seen here last night. I

these wires are attached are acted on by very fine screws, the noticed it first at 9.42. At that time the northern portion of it only revolutions of which, translated by a series of wheels into the was visible, but its intensity steadily increased, and by 9.45 the language of barometers and thermometers, are printed every arch was complete. Both at the northern and southern extremities quarter of an hour on an endless roll of paper. The whole there was a peculiar glare, extending upwards about 20°, the apparatus is set in motion by a galvanic battery, which even

winds up the clock which regulates its own action. The apex of the arch being remarkably clear and well-defined. The rainbow saded away as rapidly as it had been developed, and at

barometer is tapped before it is registered, but there is no corabout 9.50 had entirely disappeared. At the time of the occur

rection for temperature. The price is 350!. rence the western portion of the heavens was very clear, and

The barometer invented by Prof. Wild seems to bear some the moon about 8° above the horizon. Temperature cold, with

resemblance to the barograph invented by Mr. King, and now a biting wind from W.S. W.

W. R. R. B.

used at the Liverpool Observatory. Hinderton, Neston, Cheshire, Sept. 23

Ruined Cities of Central America

In the summary of the proceedings of the late meeting of the The Corona

British Association, in the issue of Nature for August 31, MAY I suggest a method of observation which would possibly is an abstract of a paper by Captain L. Brine, R.N., On the be a more delicate test than that which our own sight affords for Ruined Cities of Central America. The gallant captain is wrong ascertaining the outer limits of the corona ?

in stating that the existence of these ruined cities was unknown

Chichen Itza, which Captain Brine speaks becas e discoveries THE gradually increasing recognition of the claims of

until within a comparatively recent period. All the early

THE USE AND ABUSE OF TESTS chronicles abound in allusions to them-Remesal. Vasquez,

, , Juarrez, . Uxmal and

, of “,” Science by the Government is cause for unmingled were undoubtedly occupied places at the time Grijalva touched satisfaction to every one who is interested in the material the shores of Yucatan. Copan, although then a ruin, was and moral progress of the country. And now that the visited and minutely described by Dr. Palacios as long ago Government has set its hand to the work, it seems disposed as 1576. Captain Brine would lead us to infer that these re

to let no timorous counsels or half-measures prevail. mains have been “discovered since the expedition of Del Rio The readiness with which the demands of astronomers to Palenque in 1787.

have been met last year and this, the really admirable That these Ruined Cities were built by the progenitors of the various families of the Tzeudal or Maya stock found in Central practical instruction recently given to science teachers at America at the time of the discovery, and who are still there,

South Kensington, are evidence of the earnestness of the and that many of them were then occupied and flourishing does,

intentions of those in authority, not admit of doubt-is capable of demonstration.

In the present attitude of the Government towards Big eyed Wonder should be eliminated from modern specula- Science, however, everything is not yet as it should be. tion !

E. Geo. SQUIER Much of the practical value of this earnestness consists in New York, Sept. 14

the manner in which details are carried out, and there is one

department of the administration in which a spirit of misThe Dinnington Boulder

chief appears to delight in neutralising all efforts at improveI have been favoured with a letter from a geologist residing

ment. The recent movement to compel all candidates for at Newcastle-upon-Tyne, who kindly informs me that he has in

employment under Government to submit themselves to spected the “fossiliserous boulder," and pronounces it to be a

an educational test is in the main a good one; but it may block of carboniferous limestone.

be carried to an excessive, even to a ludicrous, extent. This gentleman, from his knowledge of the district, says, that Tests are in themselves valueless, unless they are so this limestone (underlying the coal measures) crops out about contrived as to test the possession by the candidate of seven or eight miles to the west or north west of Dinnington, those qualifications which will best fit hiin for the office from whence probably it came. The question asked of its direc

he aspires to fill. tion of travel is therefore satisfactorily answered.

There are at the present time vacancies in one of our J. BROUGH Pow

Government scientific establishments for two junior Barbourne, Worcester, Sept. 21

assistants, and the principal of the establishment was

desirous of appointing two young men who possessed the Mechanical Drawing

needful qualifications of neat and orderly habits, punctuaIn the opening address of the President of the Mechanical lity, and obliging demeanour, and a love of Science for its Section of the British Association, descriptive geometry and own sake. The establishment in question has, however, geometrical projection are both spoken of as subjects of little the misfortune to be under the control of the Board of value to the mechanical draughtsman.

Works ; and when the authorities of this department Now, being interested in the matter, I would like to ask the

heard of the vacancies, they insisted, notwithstanding nature of that special kind of mechanical drawing of which the President spoke, and which leads to mensuration and geometry,

the remonstrances of those most interested, in announcing I suppose from the address, descriptive geometry and geometrical be that the posts will, in all probability, be given to those

them for public competition. The consequence will projection will be dispensed with, seeing, as he says, that it is no loss to the mechanical draughtsman to be ignorant of the

who display the best acquaintance with English History latter. As an illustration of that real mechanical drawing which or French, but who have not proved themselves possessed he advocates, would Prof. Jenkin be kind enough to show the of a single qualification for these particular posts. This method he would adopt in the construction of a drawing which Procrustean system of measuring all men by the same would show the lines of intersection of the surfaces of a cone and standard will not answer. The inevitable result will be to sphere whose axes are not in the same plane?

fill all the square holes with round men, and all the round I can assure Prof. Jenkin that a word of advice from him will holes with square men.

As reasonably might we require always be a great boon to the hardworking student.

all the clerks in the Foreign Office to be acquainted with DRAUGHTSMAN

the properties of the chemical elements, or every assistFall River, Mass., Sept. 18

ant in the library of the British Museum to be able to

name the bones in the human skeleton ; for these are as Ice-Fleas

essential to the liberal education which every gentleman I SHOULD have thought that the “ice-fleas” described by Prof. ought to possess, as a knowledge of English History or Frankland had been almost as familiar to Alpine travellers as French. The system pursued in the British Museum, their more offensive namesakes of the châlets. They are de- which is fortunately under the control of another departscribed by De Saussure (Voyages, § 2249), by Mr. Morell, ment of the administration, would satisfy all reasonable “Scientific Guide to Switzerland," p. 275; by myself " Alpine requirements : that the principals of all establishments Regions,” p. 207, where references are given, chiefly to a paper should have the right to nominate candidates to vacancies, by M. Nicolet in "Neue Denkschriften der Allg. Schweiz. Gesellsch." vol. v. (1841); and by other writers on the Alps.

subject to a qualification test of their general acquirements. T. G. BONNEY

It is but fair that in departments where the efficiency of St. John's College, Cambridge

the subordinate officials depends so much on their willing

ness to co-operate heartily with their superiors, and on Thermometer Observation

the possession of qualities which no examination can

possibly test, the principals should have some voice in the One very hot day last summer I exposed to the sun, in the appointment of those who may probably succeed to the same position, three thermometers ; No. I was a new one mounted

offices they themselves occupy. An opportunity is thus on box wood, No. 2 was similar, but very dirty from exposure to the weather ; No. 3 is what is known as a bath thermometer, rants, who may be known as earnest and careful workers,

also given for the encouragement of young scientific aspiwith a metal scale. In the shade they all agree to about 1, but who would otherwise stand little chance of Governbut in the sun No. 2 rose about 8° above No 1, and No. 3 about the same above No. 2. Here we have a discrepancy of ment employ; about 16°, caused no doubt by the different heat absorbing and

We make these strictures in no carping spirit, but simply radiating powers of the substances on which the thermometers with a desire that the good work now commenced may were mounted. I think this may somewhat account for the not be marred by errors of administration. The only object various readings we see announced by different observers. of the system of competitive examinations, and of com

D. J. STUART pelling all candidates for Government posts first to submit

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themselves to a qualification test, is in order that these water at the bottom, and I have pointed out that such a offices may not be the refuge for genteel incompetence, surface-replacement is known to take place in the case of but may be bestowed on the most fitting aspirant. We the Gulf Stream, one portion of which directly returns fear the above facts will show that the present system is into the equatorial current, completing the shorter cirnot calculated in all cases to secure this end.

culation, whilst the other has its complement in the Greenland, Labrador, and other polar surface-currents, of which

the principal is traceable southwards nearly as far as the THE GIBRALTAR CURRENT

exit of the Gulf Stream from the Narrows, thus completMR R. CROLL having stated (NATURE, August 17)

ing the longer circulation. that, taking my own data, and having "in regard

The correctness of this “ common-sense” judgment to the Gibraltar current and Dr. C.'s general oceanic cir

was most emphatically affirmed, on the basis of profound culation, determined the absolute amount of those effects physical knowledge, by Sir William Thomson and Prof. on which his circulation depends," he has satisfied him

Stokes. It was agreed by these high authorities that in self by mathematical investigation" that the work of the the open ocean the action of wind on the surface can resistances greatly exceeds the work of gravity, and that

never produce any other than a surface movement ; the consequently there can be no such circulation as that

water propelled onwards from one part of the oceanic. which Dr. C. coniends,"— I think it well to point out that

area being replaced by a surface in flow from other parts the question of the existence of such a circulation is not

It is, therefore, for my opponents to explain how, otherto be disposed of by the calculations of even such an ex

wise than by gravity, it happens that polar water finds pert computer as Mr. Croll, but must be decided by the itself at the depth of 2,000 fathoms under the equator. collection and comparison of facts ascertained by observa- there were no movement of polar water towards the

That the bottom-temperature of the equatorial area, if tion and experiment. Now, as it happens that an opportunity has been re

equator, would be at least 20° higher than it is, may be cently afforded me by the Hydrographer to the Admiralty the Mediterranean, which is cut off from communication

asserted without the least hesitation ; the temperature of of carrying out, in conjunction with Captain Nares, of with the lower stratum of the Atlantic, [being 54° at H.M.S. Shearwater, a series of further researches on the Gibraltar current, which place beyond all doubt the corresponding depths. ouiflow of dense Mediterranean water into the Atlantic, Stokes, that when a wind blows continuously into a loch

It was agreed by Sir William Thomson and Prof. over the “ridge “marine watershed” between Capes Trafalgar and Spartel, and beneath the surface-inflow of

or fiord, so as to produce a rise of water at its head to the Atlantic water, I would submit (1) whether there must not

amount of 6, 8, or 10 feet, such an excess or vertical presbe some fundamental fallacy in Mr. Croll's computations such outflow being afforded by the continuance of the

sure produces an outward under-current; the evidence of in regard to the Gibraltar current, and (2) whether this fallacy should not destroy all confidence in the infalli- surface in-current at the rate of three or four miles per bility with which Mr. Croll credits himself in regard to hour, without any further increase in the rise of water at the general occanic circulation.

the head of the loch. This exceptional case was advanced No one can be more ready than myself to admit that by Sir W. Thomson as strongly confirming my general this last doctrine is at present only a hypothesis, resting principle, not as invalidating it'; and I would therefore on a very narrow basis of fact. But as this hypothesis recommend Mr. Croll

to test his method of investigation has been accepted as probable by such great masters in by this ascertained fact, rather than spend his time in physical science as Sir John Herschel and Sir William

demonstrating the impossibility of what he may hereafter

have to admit as no less certainly proved. Thomson, and as the means of putting it to the test will

WILLIAM B. CARPENTER be supplied by the Scientific Circumnavigation Expedition,

H.M.S. Shearwater, Malta, which (I have every reason to expect) will be fitted out by Her Majesty's Government next year, I would venture to

Sept. 29 suggest whether prudence does not dictate to the opponents of that doctrine, that they should either drop further discussion of it for the present, or that at any

SCIENCE IN ITALY rate they should refrain from attempting to demonstrate N NATURE for June 8, I sketched a short notice of

IN its impossibility.

some of the Italian scientific serials, among them the The number of NATURE which contained Mr. Croll's Annali di Chimica Applicata alla Medicina, published at letter, having also given an account of the discussion Milan. With the commencement of the present year which took place in the Physical Section of the British

the Gazetta Chimica Italiana has been launched at Association on a communication I made to it with

Palermo. The project of this publication originated in reference to this subject, I may niention that my especial Florence with a society of Italian chemists, who met there purpose in that communication was to obtain the judg- in October last, and resolved to entrust the first year's ment of the able physicists there assembled, as to a fun- “ direction ” of the magazine to Prof. Stanilaus Cannizzaro damental question at issue between my friend, Prof. of the University of Palermo. Wyville Thomson, and myself, namely, the cause of that

The Italian Chemical Gazette very nearly resembles the flow of polar water over the deepest parts of the ocean Journal of the Chemical Society of London. Like this it bottom, bringing down its temperature even under the contains, first, original memoirs ; second, translations or equator to 3305, as to the fact of which we are in entire abstracts of the most important foreign chemical memoirs ; agreement. By my excellent colleague it is considered* third, a review of technological chemistry, agricultural that this flow is due to an indraught of polar water, oc- chemistry, and crystallography; fourth, a summary of the casioned by the surface efflux of equatorial water result principal chemical journals of Germany, England, and ing from the action of the Trade Winds. To myself (not France ; fifth, miscellaneous notes that may be interesting professing more than an elementary knowledge of physics) to those who cultivate chemical science. It is published it seemed probable, on the principle of “ least action," monthly. that the surface water so removed would be replaced by The most prominent, the longest, and most interesting an inflow from some other part of the oceanic surface, of the original papers is by Prof. Cannizzaro: "His!orithat is, by a horizontal circulation, rather than by an up- cal notes and reflections on the Application of the Atomic rising of the whole subjacent mass, so as to draw in polar Theory to Chemistry, and on the Systems of Formulæ for

* See his Address on “The Distribution of Temperature in the North expressing the Constitution of Compounds." This paper Atlantic," NATURE, July 27.

is continued in the number for January, April, and May,



and is not yet completed. The following extract from the

THE CRYSTAL PALACE AQUARIUM introductory observations will indicate the spirit in which it is written : A few are still dissatisfied

with the argu- IN NATURE of April 20 last appeared a short paragraph, the dualistic to em- stating that this “enterprise, of which great scientific ploy the atomic weights of Berzelius, or the equivalents of use can certainly be made," was taking form, and that Gmelin ; and among those who have adopted the new when some of the marine animals were introduced, and system of atomic weights and formulæ, there are many the thing was in working order, a description of it would who have done so merely in a spirit of concession, and be given. make a display of scepticism respecting its intrinsic value ; The building undertaken by the Crystal Palace Aquaothers, on the contrary, push their faith to the extent rium Company was commenced in July 1870, much too of fanaticism, and give equal value to the essential late therefore to be opened when at first contemplated, and accessory parts of the system, or even cling to hypo- April 1, 1871, though at Easter last half a dozen of the theses that merely lean against it or have been discarded. marine tanks were temporarily converted into freshwater They often speak on molecular subjects with as much dog-ones, and some pike, tench, carp, eels, &c., were shown matic assurance as though they had actually realised the therein for three days ; when the place was closed, and ingenious fiction of Laplace—had constructed a micro- the progress of the works continued, and then the estabscope by which they could detect the molecules, and ob- lishment was finally opened on August 22, 1871. It would serve the number, form, and arrangement of their con- have been well if the sea-water had been in good condition stituent atoms, and even determine the direction and in the early part of the summer, so that advantage might intensity of their mutual actions. These things, which have been taken of the then exceptionally cool weather have been offered merely as hypotheses more or less to transport some of the great abundance of animals at probable, and to be taken for what they are worth as that time on the coasts of England ; but that was not simple artifices of the intellect, are valuable, and have possible, and then, when the water was fit, the weather done good service in collocating facts and inciting to became very hot, and the sending of many animals was further careful investigations that one day or other may thereby prevented. Such creatures as could be got, howlead to a true chemical theory ; but when perverted by ever, were obtained, and the opportunity is now being being stated as actual truths, they falsify the intellectual taken of the present increasingly colder season to add other education of students of inductive science, and bring re- animals constantly, so that in a short time most of the proach upon the modern progress of chemical science.” tanks will be populated.

We learned a great deal from Italy in the Middle Ages, The accompanying plan, on page 471, drawn to a scale of and may yet learn more. I earnestly commend the above about 50 ft. to i in., shows the ground occupied by the lesson to some of our laboratory aspirants, who are occu- Aquarium and its adjuncts to be nearly 400ft. long and pying themselves in ringing the changes upon organic 70ft. broad, and it is situated at the northern end of the compounds, and who afterwards describe their atomic Palace, on a portion of the site of it burnt in 1865. It is achievements as glibly, mechanically, and confidently, as of one story high, and, therefore, this ground plan shows though they had been laying bricks or piling shot. everything, except the sea-water reservoir beneath the

An interesting paper (a note it is modestly called) on Saloon GG, extending under its whole width, and run“The Absorbent Power of Red Phosphorus” is contri- ning below Tanks 9 and 10, and going lengthwise from buted to the May number, by Fausto Sestini, from the

This reservoir contains 80,000 gallons of seaLaboratory of the Royal Technical Institute of Udine. water, and the tanks above contain 20,000 gallons, in (Udine is a small town, smaller than Croydon, and situ: all 100,000, gallons weighing a million pounds; and ated about 70 miles N.E. of Venice. How many of such the fact of the aggregate contents of the tanks being only towns in England have Royal Technical Institutes with one-fourth of the contents of the reservoir, is extremely laboratories for original research ?). The author finds that serviceable in keeping the water clear, as, supposing the red phosphorus absorbs many substances without com- water in, say tank io (holding 4,000 gallons), became bining with them, after the manner of porous charcoal. turbid from any cause, it can be emptied by syphons in Thus it may be made to take up 3-369 per cent of iodine, less than an hour into the reservoir, where so comparatively a considerable quantity of sulphur, rosaniline, &c. This small a quantity of Auid would not appreciably disturb power of " chemical adhesion” may be easily and strik- the purity of so great a mass, from which, in less than ingly shown by shaking powdered red phosphorus in a test half an hour, No. 10 can again be filled, and thus all the tube containing a coloured solution of iodine in bisulphide tanks where animals exist, are, by being constantly pumped of carbon. When a sufficient quantity of phosphorus is into, day and night, from the large, clear, and cool reserused, the whole of the iodine is taken up and the solvent voir below, where there are no creatures, kept ever in good rendered colourless. Rosaline is similarly removed from order. The main aëration which is thus depended on for an etherial solution, and a portion of it may be again re- the health of the creatures, is by these means produced by covered unaltered from the phosphorus by washing with mechanical agitation, and the quantity of sea-weed necesalcohol.

sary to decompose the poisonous carbonic acid gas evolved The July number contains some further contributions from the animals, which could not be effected by mechaniby Sestini from the same laboratory, on the proportions cal agitation, is grown upon the rocks of the aquarium by of bisulphide of carbon, its solubility in water, and the the action of light on the spores of algæ existing invisibly compounds formed by its contact with aqueous solutions in the water. As the motion of the water needs to be of the oxides of the metals of the alkaline earths. Also incessant, all the machinery is in duplicate, there being some interesting communications from the laboratory of two boilers, each of four horse power, two steam-engines, the University of Siena by Prof. G. Campani, among each of three horse power, and two of Forbes's patent which is one showing that the absorption bands of an pumps, and one of each is kept ever in action, the other ammoniacal solution of carmine so closely coincide with being in reserve in case of accident. The sea-water those of blood, as to be undistinguishable in a spectro- issuing from the pumps at the rate (indicated by a scope with a scale of twenty degrees. Mr. Sorby will counter

, while a tell-tale clock furnishes evidence of the probably be able to tell us whether any difference is dis- attention of three enginemen, each working for eight continguishable by more minute examination.

secutive hours) of from 5,000 to 7,000 gallons an hour, Lieben and Rossi contribute a series of rather impor- passes in the first place into the two highest tanks, 9 and tant papers on some of the alcohols, and besides these there io, half into each, and from thence it runs, diverging are some of the ordinary miscellaneous contributions to north and south, as far as tanks 18 and 1. From 18 it organic chemistry.

W. MATTIEU WILLIAMS flows into 60, and from i into 39, in each case passing

E to H2




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