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ment of molecular weakness in the bar, the weight has and stream of opal,” reminding us of the crimson and power to bend it, and the pointer falls. By such experi- purple of the poppy, the scarlet and orange of fire and ments the exact temperature at which the metal becomes the dawn. No wonder he chides us with turning the weak, in different varieties of steel, can readily be deter- lamp of Athena into the safety-lamp of the miner, and mined.

with getting our purple from coal instead of, as of old, (2) Evidence will now be given in support of the second from the murex of the sea ; "and thus grotesquely," he case it was proposed to treat, and it will be shown that at says, "we have had forced on us the doubt that held the high temperatures the atoms of metals may truly com- old world between blackness and fire, and have combine with each other ; in fact, taking gold as a basis for pleted the shadow and the fear of it by giving to a the experiments, compounds may be formed which would, degraded form of modern purple a name from battlehad they been known centuries ago, have strangely Magenta.'” affected the history of science. When the alchemists You will remember that Faraday showed that gold, when subjected the metals to bigh temperatures, their efforts finely divided, is brilliantly coloured scarlet and purple. were mainly directed to the discovery of some substance Here is a solution of chloride of gold. Add a little disthat would either change base metals to the colour of solved phosphorus, and the gold is precipated in an exgold, or would give them the brilliancy of silver. The tremely fine state of division, which tinges the solution mediæval chemists believed that there were two distinct crimson, but if you try to remove this suspended gold substances that would effect this, "one for the white ”and you will only gain a brownish mud. However, I will give another "for the red.” Many of their writings might be you the secret hy which anyone who possesses a blow-pipe, quoted in support of this view, but a reference to Geber, a bead of gold, and a fragment of one of the most widelywho wrote in the eighth century, will be sufficient. Hé diffused metals, aluminium, may stain gold purple through pointed out that the transmuting agent “has a tincture of and through. But if you add aluminium to molten gold, you

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itself so clear and splendid, white or red, clean and in- obtain many things, as this coloured diagram and series combustible, stable and fixed, that fire cannot prevail of specimens show.' (This diagram cannot be reproduced against it; . . . and a property of the medicine is to without colour.) give a splendid colour, white or intensely citrine,” to The series of specimens showed that as the proportion of metals to which it is added.

aluminium is increased, the golden colour of the precious That was the effect expected from the transmuting metal is lessened, and when an alloy is formed with about agent, but do not think that the attempt to produce gold ten per cent of aluminium, the fractured surface of the mass arose entirely from the love of gain. The colour of gold is brilliantly white: from this point forwards, as aluminium and purple impressed men strangely, and the search for is added, the tint deepens, until Aecks of pink appear, and the transmuting agent was most eagerly pursued in times when seventy-eight parts of gold are added to twenty-two when people lived for art, in a dream of colour. The of aluminium a splendid purple is obtained, in which effort to find the secret of the tint of gold is due to the intense ruby-coloured opaque crystals may readily be same impulse which made the French in the thirteenth recognized.' Then, as the quantity of aluminium is still century manifest a keen “sensitiveness to luminous further increased, the alloys lose their colour, and pass to splendour and intensity of hue," so that, as Sir Frederic the dull grey hue of aluminium itself. Perhaps the most Leighton tells us, “a stained glass window, by Cousin, ' remarkable point about the purple alloy is its meltingwas limpid with hues of amethyst, sapphire, and topaz, point, which I have shown to be many degrees higher and sair as a May morning." The chemists were able than that of gold itself.' See diagram, Fig. 7, in to stain glass ruby and purple with gold : why should which curves of several constants of these alloys are they not impart the same glories to metals? I could I given. This fact affords strong evidence that the not hope to interest you in what follows, did I not call alloy AuAl, is a true compound, having analogies to artists to my aid ; and many will remember the glowing the sulphides, for in every other series of alloys the words Mr. Ruskin uses,' calling purple a “liquid prism | melting points of all the members of the series are 1 "The Queen of the Air," ed. 1887, p. 129; Times, December 11, 1891.

Proc. Roy. Soc., vol. I, 1891, f: 367.

I

an

lower than that of the least fusible constituent. There proportional to the density of the gas or of the solution. is one other fact of much interest connected with this Is the view of Arrhenius correct--that, if a solution be alloy. When it is treated with dilute hydrochloric acid, very dilute, the molecules of the dissolved substance are chloride of aluminium is formed, and gold is released in dissociated, act independently of each other, and behave a singularly voluminous form. The heat of formation of like a perfect gas? the gold-aluminium alloy has not been determined, but It will require years of patient work before these queshydrochloric acid, which will not attack gold, will tions can be answered ; but it appears certain, from the readily split up this compound, of which more than admirable experiments of Heycock and Neville, to three-fourths is gold ; the compound, in fact, behaves which reference has already been made, that, taking like a distinct metal, having special heats of oxidation metals with low melting points (such as tin or lead) as and chlorination of its own.

solvents, the lowering of the freezing-point of the solvent (3) Lastly, we come to the question of solutions of is really due to the bombardment exerted by the molecules metals in each other. One very remarkable instance of of the dissolved metals. the behaviour of metals at high temperatures reveals the I have extended this investigation by employing as a fact that the presence of a small amount of a metal in a solvent a mass of fluid gold, which has a high meltingmass of another lowers the freezing-point of the mass. point, and is not liable to oxidation, and the results conIn the industrial world this has long been known. firm those obtained by Heycock and Neville. Cellini tells us, for instance, that when the bronze for his There is yet one other question: When metals are great figure of Perseus, at Florence, was running out of added in small quantities to a metallic mass, may the the furnace, it suddenly showed signs of setting, and he solvent remain inert? Here is a mass of 1000 gram mes therefore threw pewter plates and dishes into the ducts of lead, and to it 15 grammes of gold, or 16 atoms for through which the metal had to pass—"a thing," he every 100 atoms of lead, will now be added. It could be says,

"never before done." The fluidity of the metal was shown that the gold is readily dissolved, and remains disimmediately increased, and he found every part of the solved, even if the lead be solidified. Now, to the fluid casting “to turn out to admiration."

lead sufficient aluminium will be added to form the The excellent work of Heycock and Neville, on the purple alloy with the dissolved gold ; the mass will be lowering of the freezing-points of metals, by the addi- well stirred, but the aluniinium will not unite with the tion of other metals, should, I would suggest, form lead ; it will nevertheless find out the gold, and, after the subject of a lecture in this Institution at uniting with it, will carry it to the surface of the bath. early day. I cannot attempt to deal with the matter Thence it can be removed, and the purple colour of here. In leading up to these questions of solution, the alloy identified, or the gold it contains can be as applied to metals, I would remind you that Lord revealed by the method Prof. Hartley ? has given us for Rayleigh told us a few evenings since that it was by detecting the presence of gold in an alloy by volatilizing no means certain that a gas rushing into a vacuous globe the alloy in a torrent of sparks from an induction coil, ever completely fills it, as there may still be tiny spaces and condensing the vapour on mica. into which "odd molecules " fail to find room to vibrate The union of the aluminium and the gold must, howin. If it is difficult for a gas to entirely fill a vacuous ever, be peculiar. Crookes 3 has shown that when this space, you would think it impossible for a small quantity alloy is used as an electrode in a vacuum tube, the gold of a metal to rapidly permeate a fuid mass of another is volatilized from the alloy and deposited as a film on the metal ; nevertheless, so far as analysis can detect, this glass, leaving the aluminium behind. does happen.

The purple alloy presents us with the most interesting It may be incidentally observed that the relations of case yet known of a molecule built up of purely metallic the ordinary gases to metals are far more intimate than atoms, but we are certain that the atoms are still those of they were formerly supposed to be, and this was proved gold and aluminium-that is, the atoms of the united by Graham's work on the absorption of gases by metals, metals remain unchanged. The interest in this substance which has often been dealt with in this Institution. To is deepened if it be remembered that our aim at the take only the case of iron, more than twenty years ago present day is the same as that of the alchemists, for we Sir Lowthian Bell showed that carbonic oxide can carry are striving, as they did, to attack and change the chemist's away iron, which is released when the temperature atoms themselves. We seek, as truly as they, to effect is raised. Ludwig Mond and Langer have since iso- the transmutations, which, as Boyle said, would "be lated most interesting compounds of iron and carbonic none the less real for not being gainful,” and employ oxide. But to return to the solution of metals in high temperatures in the hope of simplifying the molemetals.

cular structure of metals. We no longer consider gold to The method of taking autographic curves of the be the “sum of perfection," but still retain the belief excooling of masses of metal has already been indi- pressed by Geber, eleven hundred years ago, that, "if we cated in Fig. 4,” and they ought to enable much would change metals, we must needs use excess of heat." information to be gained as to what is taking place A poet also appears to have felt this, for George Herbert throughout the mass. Such curves should render it writes in the seventeenth centurypossible to ascertain which of the rival theories as

“I know . . . what the stars conspire, to the nature of solution, as applied to salts, is sup- What willing Nature speaks, what forced by fire"; ported by the behaviour of a metal dissolved in a metal. When, for instance, a little aluminium dissolves in gold, thus comparing the ordinary response of Nature to the is the analogue of a hydride formed, and, if so, is the investigator with the evidence he elicits from her by curve of freezing-points of a series of aluminium-gold heat. alloys a continuous one ? On the other hand, does the By fusing gold, and staining it "the purple of the theory advocated by van 't Hoff, Arrhenius, and Ostwald dawn," a new interest has been given to the metal which gain support, and do the molecules of the dissolved the alchemists always connected with the sun; and for metals act independently of the solvent—that is, does further proof that metallic atoms may be changed, we osmotic pressure come into play? It will be remembered must turn to the sun itself, as to a great metallurgical that the law which regulates osmotic pressure has exactly centre, where “all the elements shall melt with fervent the same form as Boyle's law—that is, the pressure is

heat." : Chem. Soc. Journ., vol. lv., 1889, P. 666 ; vol. lvii., 1890, pp. 376, 656: 1 vol. lix., 1891, p. 936.

Proc. Roy. Soc., vol. xlvi., 1889, p. 88. • Proc. Roy. Soc., vol. xlix. p. 347, 1891.'

3 Proc. Roy. Soc., vol. l., 1891, p. 88.

1 Loc. cit.

a

ON INSECT COLOURS.

cies and the normal reds, but nearer to the former. The

evidence on which this conclusion as to the nature of II.

the red in V. atalanta was founded is as follows. The N Cow it is necessary to explain the "reversion effects” red of atalanta does not change to yellow, but to the

of red, so frequently alluded to. I am tempted brown or chestnut normally present in V.cardui, or to a to give a detailed account of the experiments made in more colourless tint. The change is not similar to that this connection, but the length to which this article of red to yellow, but is a solution effect : consequently no has already run warns me that I must be very brief reversion effect can be obtained ; and this alone is almost indeed: and I will therefore content myself with giving decisive. It seems to me especially interesting that this simply the broad results. All reds and pinks (always experimental conclusion as to the nature of atalanta red omitting the last four in the table), are turned orange or is entirely corroborated by totally independent evidence yellow instantly by acids. When nitric acid is used, from the entomological side, since the connection of V. this effect is permanent; and whether the yellowed wing atalanta and cardui is exceedingly close, and there are be dried, or washed, the yellow is immovable. I have transition forms between them. kept such wings for five or six months, and they were as And now we come to the last colour-chestnut-for yellow as possible at the end of that time. In the case which a very brief account will suffice, in addition to the of all other acids, the yellow is permanent only so long details already given in the table, and the incidental as the wing is' actually acid: directly the acid is remarks made during the discussion of yellow. It must removed, the original red returns ; and thus be understood, then, that the constitution of chestnut wing may be alternately yellowed and “reverted" appears to be very close indeed to that of yellow : like as time after time. This reversion to the original in yellow, we can distinguish several stages of solubility, red may be produced either by long exposure to the air, although deepening, colour still less implies decreasing allowing the last traces of acid to drain off; or instantly solubility even than it does in yellow-a conclusion which by neutralizing the residual acid with a drop of ammonia, will be borne out by an examination of the table. Like or by copious washing. It must therefore be under- yellow, chestnut may develop into red, as has already stood that, with the exception of those cases in which been explained; and the brilliant copper colour of Lycæna nitric acid has been used, the permanency of the artificial phlæas and virgaurea appears to occupy, both in its exyellow is entirely dependent upon the presence of acid: treme solubility and its relation to the main line of developremove the acid, and the yellow vanishes. Accordingly, ment of the chestnut pigment, a position exactly analogous I have suggested the following explanation. Let us de- to that occupied by the orange of E.cardamines among the note the molecule of red pigment by X; when any acid, yellows. The only further remark that I have to make except nitric, is added, I assume that this forms with X with reference to this colour concerns V. io and V. antiopa, a so-called molecular compound: for instance, on treating which I have specially marked as notable examples. In with hydrochloric acid, we should get the hydrochloride of these species the rich chocolate colour is very soluble, but X, viz. X.(H.CI),; and it is evident that these hydro- leaves a black wing instead of a white. If chestnut had chlorides, hydrosulphates, &c., of X are yellow, although been developed from a white pigment, this would have the original X is red. To all these facts, of course, there been a grave difficulty ; but it perfectly accords with the are ample analogies known to chemistry. Next, for the re- view that the pigment has been developed, not from any suscitation of red. We must suppose—what is certainly such white pigment, but in a previously unpigmented, to all appearance very clear-that these molecular com- usually white, wing ; in these species it has been depounds are very unstable ; an easily understandable fact ; veloped in a previously black wing. I have always and that consequently the addition of even excess of water

considered the behaviour of these two species to conis sufficient to decompose them, removing the acid mole- siderably support my views of the nature of the chestnut cule, and thus restoring the pigment X to its original pigment, and indirectly of the yellow.? condition. Far more rapidly does this resuscitation occur

The main heads of the preceding pages may be very if a drop of ammonia be used, this at once combining briefly summarized as follows. Blacks and whites are not with the acid and liberating the X molecule. In the case pigment but absorption and reflection colours respectively. of resuscitation produced by slow air drying, the action The great majority of blues are also physical coloursapparently would be in some cases due to gradual chiefly, if not entirely, interference colours ; and it is evaporation, or to some process of oxidation-anyhow doubtful if there be any pigment blues at all. Some producing dissociation of the molecular salt of X. Finally, greens are also physical colours, very similar to the blues ; in the case of nitric acid, it is clear that this acid does the character of another group is somewhat ambiguous, not form a molecular compound, but, as we might expect,

although probably these, too, are physical. A third group, exercises a permanently destructive action on the ori- | is pigmental, and probably derived from yellow. All ginal pigment. Admitting that red has been developed reds are pigmental, being developed chiefly from yellow, from yellow, it is not surprising that it may be easily re- but in a few cases from chestnut ; the former are charconverted permanently into yellow by such a reagent as acterized by the reversion effect. The great majority of nitric acid. Before quitting this topic, I may point out yellows are pigmental, of various degrees of solubility that the cyanide reaction of the yellows is very sug;

or insolubility; but a few cannot at present be decisively gestive indeed as to the kind of process by which the red pronounced either physical or pigmental, and the same pigment is developed from yellow.

remark applies to the chestnuts.3 Now, as to the last four species noted in the table. In In concluding this summary of my work, I must point these, I believe, the red is not developed from yellow at all, out that it is not put forward as in any sense of the word but from its close analogue, chestnut. Up till very recently, final, even so far as it goes, but merely as a basis of I supposed V. atalanta to be the only representative of systematic inquiry, in various directions. Up to the such development, and was rather surprised that yellow present, almost nothing at all has been known about the should so commonly develop into red, and chestnut so behaviour or character of these colours; now I will dare rarely. But recently I have found that Anartia amalthea "There is similar evidence in the case of Anartia amalthea. Two is exactly identical in behaviour with V. atalanta, whilst

specimens of this were sent me for experiment. One was marked with a

chestnut band, and one with a scarlet. This scarlet was at once changed Heliconius amaryllis seems half-way between these spe- into the chesnut normally present in the other.

? I am disappointed at having as yet come across no yellow species ' Continued from p. 517.

analogous to V. io. But in this connection I may call attention to the 2. A full account of these experiments will be found in the Entomolngist, behaviour of the green species of Cidaria, which are changed to a brownishxxüi. Pp. 39-40 and 53-59.

grey: It is possible that these greens may be descended from yellow 3 I have used hydrochloric, sulphuric, acetic, phosphoric, hydrofluosilicic, developed on an originally dark wing. and oxalic acids, in these experiments.

3 Cp. the instances of Vanessa io and antiopa.

to hope that at least a basis of operations has been am planning various lines of research suggested by my found. May I also venture to ask that any other investi previous work. As to the various other orders of insects, gators who may not have already been working on this I shall be delighted if other workers who may have subject will do me the favour of allowing me for a time opportunities, that I have not, of obtaining abundant to continue my researches alone—so far, that is, as con material, will take up the work, and determine how far my cerns the Lepidoptera, both imagines and larvæ-for I conclusions will hold for these other orders also.

TABLES OF RESULTS, 1

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Do.

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cies

stone

carda-; Rich orange

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1

Dun grey.

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&c.

cies

orange Not

R.

R. Apatura iris

Chiefly unaltered ; gloss R. Papilio machaon Palish yellow White.
destroyed by KHO.

Heliconius amaryl

Very pale yellow Do...
Trepsichrois lin- | Rich purple The glow much dulled.
næi
velvet glow

Catopsilia catilla Light sulphur
Hypolimnas bolina
The glow much dulled or

l'anessa antiopa

Dull palish

Whitish. unaltered.

yellow Hypolimnas sala

Charaxes athamas

Light sulphur White or towards whitish.
Violet
mis
Dull steel blue.

Not

Tenias nise and Lemon yellow
Papilio-six spe- Bright and pale (Bronze; leaf brown; or

Pure white.
vabella

+
blues.
steel blue; &c.

Delias eucharist
Morpho menelaus Brilliant blue
Less brilliant

and hierte

Yellow

Do.
Papilio machaon Dullish blue
Greyish.

Hebomoia glaucippe Deep orange Perfectly transparent.
Limenitis sibylla

Do.
Do.

Colias edusa š?

Pure white.
Smerinthus ocella- Do.

Rich yellow
Greyish or unaltered.

Gonepteryx cleo-Bright brim-
tus

patra

Practically white. N. Catocala fraxini

Dull blue

No marked alteration.
R.
Vanessa-four spe- Blue
(Paler or unaltered; de- B.

Deep yellow
Hasis
sp.

Unaffected or nearly white

Not cies

stroyed in 1'. antiopa. Lycæna-five spe- Various blues

R. Euchloe
(Usually slate colour; occa

White.
cies
sionally greenish.

mines
Gonepteryx
cleo

Through brimstone to

Do. patra

white.
R. Parthenos gambri-)
sius (upper sur-

Metallic
(Purplish bronze or
Gonepteryx rhamnik Bright brim-

Towards whitish.

stone
green
face)

blackish.

Colias hyale

Pale brimstone + Lighter or fairly white.
Dark metallic

Polyommatus
Hesperia sp.

(Scarcely affected or toDo.

Orange ale ris

wards whitish.
green
B. Urania fulgens

Do.
Do.

B. Hepialus humuli

Dullish yellow {Sickly yellowish; nearly Bronze yellow

transparent. R. Papilio polyetor

Brownish or blackish. green

G. Rumia cratoegata

Pale brimstone

Towards whitish.

No t
Parthenos gambril
sius (below)

Sage green
Dun brown.

Camptogramma

Dull orange

Towards or whitish.
bilineata

Not
Limenitis procris
Do.

Hyria auroraria Dull yellow

Whitish or white.
S.

Glittering green Bronze brown.
Ino statices, &c.

Abraxas
R. Argynnis paphia,/ Deep foliage.

gross11Do.

Palish orange

Towards white or white.

lariata green

(Unaffected, or paler, cr Almost arsenic

l'enilia maculata

Yellow
Thecla rubi
Brown, like upper surface.

white,
green
Papilio-four spe.

Angerona
Whitish; white; or

pru- Brownish
Leaf green

Dulled or unaffected.
naria
yellow.

Papilio asterias
Very pale green

Orange yellow Usually unaltered.
Eromia argia

Paler or whitish.
ish

Ornithoptera dar

{Practically unaltered; but sius

Crocus gold
Whitish ; ochre yellow in

some probably dissolved. N. Halias prasinana Green

Transparent or rather ilone case.

N.
Eudryas grata

Yellow

faded.
M. orion; and D.

Do.
White.

\Much paler, or towards aprilina

B. Tithonea haumoni Do. Not

whitish. G. Larentia, &c.

{White; occasionally

Do. several species

yellowish white.

The following yellow or orange-yellow species are almost or entirely Cidaria miata,

unaffected :

Brownish grey. &c.

(R.) Papilio thoas, polyzenes, and philenor; (B.) Deiopeia bella, CalliT. Tortrix viridana | Do.

Whitish.

morpha hera (no t), Arctia villica, Citheronà regalia; (N.) Xanthia R. Euchloe

sılago, Triphana pronuba (no t), Heliaca tenebrata.

Black. mines

R. Vanessa io

and

Chocolate Blackish. N.B. antiopa

I', urticce
S. Smerinthus, &c.-

Rich chestnutish Whitish.
Pink
several species
Yellow or yellowish.
Argynnis paphia Rich chestnut

(Whitish; faded; or

and selene B.

I nothing.
Deiopeia bella

Do.
Yellow.
Danais chrysippus! Do.

ĮVery faded; or whitish
Actias luna

Do.

Do.
Attacus cynthia Do.
Colourless or faded.
and hegesippus

grey.
Hepialus humuli

Dull chestnut White or transparent.
Do.
Faint orange.

Athyma nefta
Hyria auroraria

Canonympha pam- Pale chestnut
Do.
Yellowish or whitish.

Whitish or white.
Aristelia rubricata Do.
Dunnish colour.

phila
K.
Parnassius apollo Red

Orange.

Hesperia sylvanus Chestnut Faded or white,
Delias hierte and Red (*)

Lycuna phlæas anal
Yellow: then white.
eucharis

virgaurea

Brilliant copper Much faded or whitish,

l'anessa cardui Chestnut Faded or whitish.
Papilio-various

Crimson, scar- Yellow, orange, &c.
species
let, &c.

Epinephile tithonus

Do.

Faded more or less.
S.

and janira
Red
Orange.

Satyrus megara

Yellow chestnut Little faded only. dule B.

Faded or very faded in.
Arctia caia

Do.
Atella phalanta Rich chestnut

deed.
Euchelia jacobeo Do.

Do.
N.

Rich chestnut Very faded indeed.
Catocala nupti Do.

Do.
Xanthia silago Reddish
| Yellow.

Yellow chestnut Dulled.

| Athyma penus K. Papilio vertumnus Pale red

Pale ochrish bread

G.
and constolochia
colour

and chocolate
Heliconius amaryl- Scarlet

Brown: finally white.

The following species are chiefly or wholly unaffected :lis

(S.) Philampelas atkemon, Darapsa myron ; (R.) Dione passifiora; (B). Anartia amalthea Do.

Chestnut.

Orgyia antiqua, Bimbyx quercus; (N.) Orthosia macilenta, Mamestra Vanessa atalanta Do.

Acardui" brown. oleracea; (G.) Cidaria sufumata, Coremia ferrugata and minutata. ' These tables afford only a very condensed summary of results ; for fuller details vide Entomologist. The initials R., B., N., G., S., T. in first column signify respectively Rhopalocera, Bombyces, Noctuæ, Geometræ, Sphingida, and Tortrices. The asterisk (*) against various red species signifies "reversion effect," and the mark t against certain yellow species that the cyanide effect" has been obtained ; similarly, Not that no cyanide effece can be obtained with that species.

F. H. PERRY COSTE.

Do.

carda-} Pseudo-green

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EXAMINATION OF THE STANDARDS OF at the Houses of Parliament without the risk of removal

MEASURE AND WEIGHT IMMURED IN from the building. It was, indeed, a condition of the THE HOUSES OF PARLIAMENT.

examination that the immured standards should not be

removed from the custody of the Clerk of the House. A FORMAL examination of the standards of measure The balance used indicated differences of weight ap

and weight which are immured in the Houses of proaching oʻ0005 grain, although, unlike other balances Parliament was made on Saturday last, of which some of precision, this balance was inclosed in a closely-fitting account may possibly interest our readers.

copper case, so that disturbance by currents of air might In the “New Palace at Westminster” there were de- be avoided as far as possible whilst the examination was posited in the year 1853 a copy of the “Imperial being made. The mode of comparison of the yard standard of the yard measure” and also a copy of the measure was that adopted by Baily and Sheepshanks in * Imperial pound weight.” In the same year similar 1843-48, Gauss's method of weighing being followed ; copies of the Imperial standards were also deposited and the temperature and atmospheric pressure were inwith the Royal Society, at the Royal Observatory, and at dicated by instruments verified at the Kew Observatory, the Royal Mint respectively. Such copies of the standards The immured standard yard, like the Imperial yard, were deposited in accordance with the recommendations was found to be a bronze bar about 38 inches in length, of a Commission appointed in 1843 to superintend the marked "Copper 16 oz., tin 24, zinc i. Mr. Baily's metal. construction of new Parliamentary standards of length No. 4 standard yard, at 61° 98 Fahrenheit. Cast in 1845. and weight intended to replace the original Imperial Troughton and Simms, London ”; the length of the yard, standards which were destroyed by the fire at the old or of 36 inches, being determined by a straight line or House of Commons in 1834. The new Imperial standards distance between two fine lines marked on gold studs or were subsequently legally recognized by the Act 18 and plugs which were inserted at the bottom of two holes or 19 Vict., c. 72 (1855), and more recently by the Weights wells at about half an inch below the surface of the bar. The and Measures Act of 1878.

bar was found to be supported on bronze rollers, placed The Act of 1878 requires an inter comparison of under it in such manner as best to avoid flexure of the bar. the copies of the Imperial standards which are de- The immured pound weight, like the Imperial pound, posited with the Royal Society, and at the Royal Obser- was found to be a cylinder of platinum about 1'35 inch in vatory, and the Royal Mint, to be made once in every height and 1'15 inch in diameter, having a density of ten years; and such inter-comparison has been recently 21:1516; and being (in 1856) 0:00314 grain lighter than the duly made under the directions of the Board of Trade. Imperial standard deposited with the Board of Trade. It appears also to be practically necessary that the Both standards were placed in mahogany boxes; the standards immured at the Houses of Parliament should pound weight being wrapped in Swedish filtering paper, be examined at certain intervals, examinations having and inclosed in a silver-gilt case, which was further inbeen made in the years 1865 and 1872; and the ex- closed in a solid bronze box. The mahogany boxes were amination which was made on Saturday last in the inclosed in a leaden case, which was re-inclosed in a presence of the Speaker, the President of the Board of sealed oak case. Trade, and other representative authorities, was therefore Although the actual result of the examination on the first that has been made for the past twenty years. Saturday could not then be made known to those pre

As yet we can make no reference to natural elements sent, it was stated that the immured standards were for the values represented by such standards as those found to be in the same condition as when they were above referred to. The earth's dimensions (as the ten previously examined in 1872, and were to all intents and millionth of a meridian), or a physical quantity (as the purposes unchanged since their original deposit in 1853. length of the seconds pendulum), cannot at present be | The official report of the Board of Trade, which will be fixed or redetermined with sufficient accuracy for metro shortly issued, will state the full particulars of the exlogical purposes; and we have still therefore to rely on the amination. length and weight of certain arbitrary or material stand- After the comparisons of the standards had been comards placed in the custody of selected authorities. As pleted, the immured standards were replaced within the all such material standards-whether made of iridio- oak case, which was then replaced in an inclosure or platinum, quartz, gold, or other accepted materials—are cavity prepared for it in a recess under a blank window liable to alteration by time or circumstance, it becomes on the right-hand side of the second landing leading from the duty of the custodians of such standards to assure the lower waiting hall up to the Commons Committeethemselves from time to time that their standards are rooms; the rabbet of the inclosure was then covered unaltered, so far as any intercomparison of material with lime putty, the front stone being inserted and standards may afford evidence of their constancy; and driven into close contact with the rabbet so covered, such was the object of the examination on Saturday last, liquid plaster of Paris being poured in so as to fill all when the Board of Trade had their standards compared the joints of the front stone. with those immured at the Houses of Parliament.

We are glad to see from a paper recently laid before The history of these Parliamentary standards may be both Houses of Parliament that the Board of Trade also found in the classical contributions of the late Astro possess authoritative copies (prototypes nationaux) of the nomer-Royal, and Prof. W. H. Miller, to the Philosophical international standards of the metre and kilogramme; Transactions of the Royal Society (Parts III. for 1856 and and that metric weights and measures -- now also of the 1857); a history that has largely developed scientific in- highest importance in this country--may be accurately quiry in such direction, as may be instanced particularly verified by comparison with such standards. by the creation and work of the International Committee of Weights and Measures at Paris.

On Saturday the examination of the immured standards was conducted by the officers of the Standards Department of the Board of Trade, who, for the purposes of the

NOTES. examination, had provided a microscopic-comparator and a balance of precision. The comparator had in

MR. BALFOUR is expected to make a statement in the House it nothing new, and indicated differences of length ap- of Commons this evening about the Royal Commission to which proaching to oʻ00001 inch, excepting that it was portable, the question of a Teaching University in London is to be so that the comparison of the immured standard yard referred. He hopes to be able to give the terms of the reference with the Board of Trade standard might be then made as well as a complete list of the members of the Commission.

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