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- MARCH 12.-" The Currency Policy of India." W. WORBY BEAUMONT, Mem. Inst.C.E.,

By J. BARR ROBERTSON. SIR EDWARD A. || “ Mechanical Road Carriages.” Four LecSASSOON, Bart., M.P., will preside.

tures. APRIL 23. — " The Province of Sind.” By |

April 27, May 4, 11, 18. HERBERT Mills BIRDWOOD, C.S.I., M.A., LL.D.

MAY 14.-“The Province of Assam.” By Sir CHARLES JAMES LYALL, K.C.S.I., M.A., LL.D.

MEETING FOR THE ENSUING WEEK.

MONDAY, JAN. 5.. Chemical Industry (London Section). COLONIAL SECTION.

Burlington-house, W., 8 p.m. 1. Dr. J.T. Hewett,

"Note on the Fluorescence of Naphthalic Anhy. Tuesday Afternoons, at 4.30 or 5 o'clock :-

dride." 2. Dr. J. Lewkowitsch, “The SaponificaTUESDAY, FEBRUARY 10, at 5 p.m._"Women in

tion of Fats and Oils by Means of Dilute Acids." Canada.” By the COUNTESS OF ABERDEEN.

Camera Club, Charing-cross-road, W.C., 87 p.m. TUESDAY, MARCH 31, at 4.30 p.m.—“ British

Mr. J.'W. Woodall, “Nautical Astronomy, from a

Yachtsman's Point of View." North Borneo." By HENRY WALKER, Commis.

Victoria Institute, 8, Adelphi-terrace, W.C., 47 sioner of Lands, British North Borneo.

p.m. The Rev. Professor D. S. Margoliouth, TUESDAY, MAY 5, at 4.30. p.m.-“ Preservation

· Forecast of the Future of Islam.” of the Species of Big Game in Africa." By E.

London Institution, Finsbury-circus, E.C., 4 pm. North Buxton.

(Juvenile Lecture.) Rev. Canon Benbam, “Old

London Houses.” (Lecture I.) Date to be hereafter announced :— . TUESDAY, JAN. 6...Royal Institution, Albemarle-street, W., • Uganda." By HERBERT SAMUEL, M.P.

3 p.m. (Juvenile Lectures.) Prof. H. S. Hele
Shaw, "Locomotion-on the Earth, through the

Water, and in the Air.” (Lecture V.)
APPLIED ART SECTION.

Pathological, 20, Hanover-square, W., 8} p.m.
Tuesdays, at 4.30 or 8 o'clock.

WEDNESDAY, JAN. 7...SOCIETY OF ARTS, John-street,

Adelphi, W.C., 5 p.m. (Juvenile Lecture.) Prof. JANUARY 20. 8 p.m.-“ Principles which should

E. B. Poulton, “Means of Defence in the Struggle guide all Applied Art.” By G. F. BODLEY, R.A.

for Life among Animals.” (Lecture II.) FEBRUARY 3. 8 p.m.-" The Teaching of Artistic

Geological, Burlington-house, W., 8 p.m. Crafts connected with Books." By DOUGLAS

United Service Institution, Whiteball, S.W., 3 p.n.

(Juvenile Lecture.) Lieut, Henry Chamberlain, COCKERELL.

R.N., “The Siege of Delhi, 1857" FEBRUARY 17. 8 pm.-" Heraldry in Decora

Obstetrical, 20, Hanover-square, W., 8 p.m. tion." By GEORGE W. Eye, A.R.E. LEWIS

London Institution, Finsbury-circus, E.C., 4 p.m FOREMAN DAY will preside.

( Juvenile Lecture.) Rev. Canon Benham, “ola MARCH 17. 4.30 p.m._“ Artistic Fans." By

London Churches." (Lecture II.) Miss HANNAH FALCKE.

THURSDAY, JAN. 8...Antiquaries, Burlington-house, W.,

81 p.m. APRIL 21.

Civil and Mechanical Engineers, Caxton-hall, West· MAY 19. 4.30 p.m.-" The Mounting of a Play”.

minster, S.W., 8 p.m. Mr. A. Marsball Arter, (Stage Costumes and Accessories). By PERCY

“ Indicating High Speed Engines."

Royal Institution, Albemarle-street, W., 8 p.m. MACQUOID, R.I.

(Juvenile Lecture.) Prof. H. S. Hele Shaw,

" Locomotion-on the Earth, through the Water, CANTOR LECTURES.

and in the Air." (Lecture VI.) Monday Evenings, at Eight o'clock :

Electrical Engineers, 25, Great George-street, S.W.. JULIUS HÜBNER, “Paper Manufacture.”

8 p.m. 1. Mr. W. B. Esson, “Notes of Recent

Electrical Design." 2. Mr. E. K. Scott, “Notes Four Lectures.

on the Manufacture of large Dynamos and AlterLECTURE I.--FEBRUARY 2.--History—Cellulose

nators.Raw materials-Boiling, washing, breaking, and

Mathematical, 22, Albemarle-street, W., 8p.m. bleaching of rags-Esparto-Straw.

Camera Club, Charing-cross-road, W.C., 87 p.m.

Mr. Horsley Hinton, “Some Practical Aspects of LECTURE II.-FEBRUARY 9.-Soda recovery

Pictorial Photography." Manila hemp-Jute and other raw materials-Me- FRIDAY, JAN. 9 .. United Service Institution, Whitehall, chanical wood-Wood cellulose-Beating-Sizing

S.W., 3 p.m. (Juvenile Lecture.) Dr. T. Miller Loading-Colouring.

Maguire, “The Recent Campaigns in Tirah, LECTURE III.-FEBRUARY 16.-Stuff-chest

Burmah, and China."

Geographical Association, College of Preceptors, Regulator - Sand-tables - Strainer - Hand-made

Bloomsbury-square, W.C., 31. p.m. Annual paper-Fourdrinier paper machine.

Meeting.. 1. Address by the Chairman, Mr. LECTURE IV.-FEBRUARY 23.- Single cylinder

Douglas Freshfield. 2. Sir John Cockburn, "The and other types of paper-making machines-Finishing

Australian Commonwealth."

Astronomical, Burlington-house, 8 p.m. - Cutting-Statistics—Paper-testing-Experimental

Philological, University College, W.C., 8 p.m. paper making.

London Institution, Finsbury-circus, E.C., 4 p.m. Prof. J. A. FLEMING, M.A., D.Sc., F.R.S.,

Juvenile Lecture.) Rev. Canon Benham, “Old “ Hertzian Wave Telegraphy in Theory and

London and the People." (Lecture III.).

Clinical, 20, Hanover-square, W., 8% p.m. Practice.” Four Lectures.

SATURDAY, JAN. 10... Botanic, Inner Circle, Regent's-park, March 2, 9, 16, 23.

N.W., ji p.m.

Journal of the Society of Arts, |

to render an animal conspicuous to its enemy, easily recognised, and easily remembered. They are invariably associated with some

exceptional mode of defence, such as an No. 2,616. Vol. LI.

unpleasant taste or smell, irritating hairs, stings, the poison fang, &c. When an enemy

has once experienced any of the unpleaFRIDAY, JANUARY 9, 1903. sant methods of protection it signally desires

to avoid such prey in the future, and then the

conspicuous warning appearance has the All communications for the Society should be addressed to advantage that it is readily learnt and rememthe Secretary, John-street, Adelphi, London, W.C.

bered. And it is a great advantage to animals with a warning appearance, that their enemies

should learn their lesson easily, for this means Notices.

a small waste of life instead of a large waste. It must not be supposed, however, that warning

colours appeal to all enemies in the same way, NEXT WEEK.

for even the most distasteful animal will have

certain foes which destroy it, in spite of the · WEDNESDAY, JANUARY 14, 8 p.m. (Ordi distastefulness. nary Meeting.) Professor W. SMART, LL.D., Good examples of warning colours are seen “ Industrial Trusts.” Sir Robert GIFFEN, in the conspicuous black-and-white American K.C.B., LL.D., F.R.S., in the chair.

skunk (Mephitis) defended by the power of Further details of the Society's Meetings will omitting an intolerable odour, in the yellow and be found at the end of this number.

black salamander, and in many conspicuous caterpillars, moths, and butterflies. In poison

ous snakes it is common for the approaching CIVTOR LECTURES ON PHOTO

enemy to be warned off by an intimidating GRAPHY AS APPLIED TO ILLUS

attitude, as in the cobras, or by sound as in the TRATION AND PRINTING.

rattle-snake or in the Indian Echis. Animals

which can bite, such as lizards, or strike hard, Mr. J. D. Geddes's Cantor Lectures on

such as large birds, are also apt to resort to “ Photography as Applied to Illustration and

intimidating attitudes. Even large caterpillars Printing ” have been reprinted from the Fournal. The pamphlet (price One Shilling)

may assume a cobra-like appearance, but this

is, as a rule, pure can be obtained on application to the Secretary,

imposture (protective

mimicry). Society of Arts, John-street, Adelphi, London,

Another interesting point about warning W.C.

colours is the tendency for the same colours A full list of the Cantor Lectures which have

and patterns to be used over and over been published separately and are still on sale

again in the same country, so that enemies can be obtained on application to the Secretary.

have not to learn as many appearances as there are specially defended animals. This results in the further saving of life during

education, as was first pointed out by the JUVENILE LECTURES.

great German naturalist Fritz Müller. Thus, The second and last lecture of the course of distasteful butterflies often gain the same Juvenile Lectures on the “ Means of Defence colours and patterns, and so do the stinging in the Struggle for Life among Animals," was insects, strongly-smelling bugs, and the most delivered on Wednesday, the 7th inst., by highly protected beetles. Professor EDWARD B. POULTON, M.A., D.Sc., A very remarkable side of the subject has F.R.S.

only recently been investigated. Certain The special subject of this lecture was “On | African butterflies which are beautifully conthe ways in which animals warn their enemies cealed from their enemies, and live in the and signal their friends."

winter season (e.g., Precis sesamus), are , The object of warning colours and attitudes | proved to be the same species as certain is the exact opposite of the concealing colours others which are extremely conspicuous, and illustrated in the first lecture ; for they seem fly during the moist summer (Precis octavius).

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In fact, one species of butterfly, having many generations in the year, produces conspicuous

| Proceedings of the Society. generations in the summer, and concealed generations in the winter. The one has been bred from the other in Rhodesia by Mr. Guy Marshall. This extraordinary alternation can

CANTOR LECTURES. be explained by supposing that the butterfly is moderately unpalatable to insect-eating

“THE FUTURE OF COAL GAS AND animals, so that it is to the advantage of the

ALLIED ILLUMINANTS.”. generations which exist in a time of plenty to

BY PROFESSOR VIVIAN B. LEWES, warn their enemies, but to those flying in a

Royal Naval College, Greenwich. time of comparative scarcity to hide from their enemies.

Lecture III.-Delivered December 8th, 1892. Another kind of marking is beneficial in The alterations which are taking place in directing the attention of an enemy away from

the conditions under which coal gas may be a vital part, such as the head or body. Thus used for illuminating purposes are so entirely the tails of lizards easily come off, and then dependent upon the adoption of the incandesbecome themselves most active, jumping about cent mantle as a means of developing light, with the greatest vigour. They probably dis- that one of the most important questions to be tract the attention of an enemy from an discussed must of necessity be the relation escaping lizard. Similarly, light patches of existing between illuminating power, calorific colour, eye-spots, and tail-like projections value, and the light that can be evoked from on the wings of butterflies divert the at- the gas when burnt in an atmospheric burner tention of enemies from the vital structures. by means of the incandescent mantle. Certain species of hermit crabs attach to At first sight there seems to be a wide their shells in which they live, other animals discrepancy between observers on this point, with special defences and bright warning and the literature of the past two or three colours, such as stinging sea-anemones, or

years leaves one with a feeling of hazy ununpalatable sponges. This corresponds to the certainty as to what relations really exist beuse of foreign bodies for the purpose of con

| tween the character of the coal gas and the cealment, as illustrated in the first lecture.

| light which the mantle will emit from it. Recognition markings for, as it were, signal Herr W. von Oechelhaeuser came to the ling to friends or other individuals of the same

| conclusion from experiments made upon the species are probably much less common than Dessau gas that a reduction in the illuminating warning colours. They are most fully developed power of the gas causes an increase and not a in animals which go about in numbers and decrease in the candle power of the Welsbach whose safety depends upon keeping together light. These experiments we will discuss later or on the younger and less experienced follow on. Some time later Dr. Bunte read a paper ing the older to a place of safety.

before the International Gas Congress in Paris, The CHAIRMAN (Mr. R. Brudenell Carter, in which he pointed out that the changes in F.R.C.S.) proposed a vote of thanks to Prof. composition of gas, which reduce the illuPoulton, for his interesting course of lectures, minating power in flat flame and argand which was carried unanimously.

burners to a very great extent, have but little
effect in producing differences in the illumi.

nating duty of the Welsbach burner, and he
LIST OF MEMBERS.

showed by photometric measurements that the The new edition of the List of Members of the

gas supplied in Berlin, Charlottenburg, Society is now ready, and can be obtained

Dessau, and Karlsruhe, although varying in

illuminating value from 7.7 candles up to 10'9, by members on application to the Secretary.

gave, in spite of this relatively wide divergence
in illuminating value, no difference in the light

obtained from the mantles. He also showed COVERS FOR JOURNAL. that the calorific values of these gases was very For the convenience of members wishing to nearly equal. A series of papers by Messrs. bind their volumes of the Journal, cloth White, Russell and Travers, in America, gives covers will be supplied, post free, for is. 6d. | the results of a research on the incandescent each, on application to the Secretary.

mantle and its behaviour, and they came to

the conclusion that the light emitted by the the expense of the oxygen from the outer mantle has little or no relation to the illumi air. nating power of the gas when burnt per se Such a flame, however, is not the best that as a luminous flame, and will increase almost can be employed for heating the incandescent directly with the nett calorific value, the in mantle. If the air supply be further increased, crease being at the rate of i candle per cubic the inner zone, in which the primary combusfoot for every 4 calories increase in the nett tion is going on, shrinks in size and becomes heating value.

green in colour, and in an ordinary atmospheric I especially notice these three sets of burner, such as is used in laboratories, any observations, as in each case the work was further increase in the air supply before comcarried out apparently with the necessary pre bustion causes the flame to flash back to the cautions that should be taken in securing bottom of the burner. But with various forms accurate results. But there have also been a of burners for incandescent mantle heating, large number of experimental determinations arrangements are made which prevent this, made, in which neglect of such important and the quantity of air can be still further factors as the regulation of the air supply in increased. The popular idea of such burners the burner and the initial gas pressure have as the Kern is, that practically the whole of led to still more chaotic results.

the air needed for the combustion is mixed In order fully to grasp this most important with the gas before it burns at the burner top. side of the question, and satisfactorily to This, however, is an entire mistake, and if determine the real effect produced, it is neces. such a result could be obtained, it would defeat sary to consider the factors which govern the its own purpose. atmospheric burner, and produce from coal The best result is obtained from the incangas the non-luminous flame which heats our descent mantle when a little over threemantle.

quarters of the requisite quantity of air is In a lecture on the theory of the atmospheric mixed with the gas. This gives an inner zone burner which I gave before the Incorporated of a bright green, which appears to seethe Gas Institute in 1897, I pointed out that the and boil on the gauze top of the mantle burner, portion of the bunsen flame which heated the whilst the products of incomplete combustion mantle, no matter what the composition of the escaping upwards from this zone consist of original coal gas and the amount of hydro

Water vapour .... carbons which it contained, if the burner were

Nitrogen............. properly regulated as regards the air supply,

Carbon monoxide ....... consisted, as far as the combustible consti

Hydrogen .... tuents went, of carbon monoxide and hydrogen,

Carbon dioxide .............. so that leaving out of the question the initial heat given by the incomplete combustion in | It is this mixture escaping red hot from the the inner zone, water gas burnt without any inner zone which, in its combination with the admixture of air, would prove a highly success. oxygen of the outer air, excites the mantle to ful mcthod of developing light from the mantle. incandescence. If the aeration of the gas

The chemical changes taking place in the before burning is pushed beyond this point, flame of the atmospheric burner were first the candle power yielded by the mantle falls studied by Blochmann, whilst Prof. Smithells instead of rising. and I have of late years done considerable Various theories have been put forward to work on the subject. The actions taking place explain the wonderful light emissivity of the are perfectly clear. An ordinary 16 candle incandescent mantle, the latest one being that coal gas requires from 5.5 to 6 times its own of Messrs. White, Russell, and Travers, who volume of air for its complete combustion. conclude that the oxide of cerium is held in a If about half this volume of air is caused to state of solid solution by the oxide of thorium, mix with the gas before ignition at the burner and that this exerts a specific influence in head the gas is consumed in two stages which altering wave lengths, so that the mantle emits give the dual character to the flame, the inner more blue and green rays and fewer red rays, cone being produced by incomplete combus i.e., converts more of the energy of the flame tion at the expense of the previously admixed into light and less into heat than does the ordiair, whilst the outer cone is due to the com nary flame that owes its incandescence to bustion of the products of incomplete combus- carbon particles. tion from the inner zone, which takes place at ! For my own part I do not agree with this,

.........

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Illuminating

Calorific
Value

Candle Power in mantle per

Gas.

Cand- les by

les at

5 c. ft.

16

Gross. Nett. Ordin- Ad. candle rate.

177

172

| 155'3

20 6

and am in entire accord with the theory of by the mantle is so small as to be far overProfessor Bunte that the process of combustion shadowed by the alterations in light due to and the heat given thereby are stimulated by the inequality of shape in the mantle and other catalytic action of the material of the mantle ; factors apart from the calorific value of the and I consider that Luggin's experiment, gas. which showed that the Welsbach material can The record of one experiment will show be brought by catalytic action in a cold mixture what I mean. A good mantle on a “C” burner of gas and air to a state of full luminescence, was tested with a 1707 candle power gas and to be conclusive evidence on this point.

gave 20:6 candle per foot of gas. 40 volumes of Taking these factors with regard to the con blue water gas were then added to 100 of the coal dition of combustion as existing in the atmo gas, and time given to complete the mixing spheric burner flame, it is evident that the of the two gases; on again testing under calorific value of the original gas will exert a precisely the same conditions as before the certain influence on the temperature of the mantle gave 1707 candles per cubic foot of inner zone of the flame, and that the super gas, and the light became a little unsteady. heating action of this upon the combustible A collar was fitted to the air holes of the constituents of the escaping gas and the burner, and on regulating the air supply until escaping products of combustion, will influence the mantle gave the best results, a light of the temperature existing on and close to the 20*1 candles per cubic foot was obtained. The surface of the mantle, so that, supposing the details of the experiment are:--burner to be working under the best conditions of air supply, the light emitted will follow the calorific value of the gas. But the difference

Power.

Calories. cubic foot air. between the illuminating value given will only

1. Cand be a very small proportion of the difference between the calorific value of the two samples of

| ary. justed

rate. gas. I showed in 1900 that the effect of the Coal gas......... 1746

20*6 superheating influence of the inner zone

20*1 upon the outer portion of the flame, is clearly demonstrated by using a Smithell's tube, by which the outer and inner zones of The pressure was if inches in each case, and an atmospheric flame can be widely separated. | the gas was burnt at the same rate of flow, Under these conditions, the superheating vie., 4 cubic foot per hour in both experiments. effect of the inner zone is reduced to a It is seen in this case that the loss of light minimum, and a mantle heated in the outer given by the mantle was half a candle for a zone gives but a poor light, whilst on allow loss of flame illuminating value of 6•2 candles ing the inner zone to rise in the tube, the if tested by the 5 cubic feet rate, or 3.6 candles luminosity of the mantle increases, until, if tested in a rational manner. There was, when it has resumed its normal position in moreover, a loss of calorific value in the gas the centre of the flame, the mantle emits its equal to 33.5 calories. Therefore, according full light.

to the ratio given by Messrs. White, Russell, It is clear from this that the superheating and Travers, the 20:6 candles per cubic foot by the inner zone plays a part in the light

ought to have been reduced by 33'5 or 8.3 emitted by the mantle. But in all the experiments I have made with gases of varying candles, so that 11.8 and not 20'I candles illuminating and calorific values, I have failed should have been found. to find any alteration in the light yielded by . It is clear, therefore, that if care be only taken the mantle that would justify the adoption to properly adjust the burners, air supply, and of such a ratio of decrease as that given by mantles to the gas supply of a district, which Messrs. White, Russell, and Travers, i.e., one could easily be done, the differences due to candle per cubic foot for a diminution of the lowering of the candle and calorific value 4 calories, and I am forced to the conclusion of the gas become so small as to be negligible. from my own experiments that for calorific To my mind this is a convincing proof of values such as mixed gases between 12 and the truth of Dr. Bunte's catalytic theory of 18 candle power possess, with proper air ad. incandescence. If the light emitted by the istme 1: to the burger the loss of light given | mantle be due not so much to the temperature

Coal+water

gas (100

14'0

136

12181707

40)

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