In the preceding 149 molecules it will be noticed that there are two of each of the following, phenylethylamine (Nos. 42, 44), benzyl acetate (Nos. 56, 57), nitrobenzene (Nos. 119, 120), benzoic acid (Nos. 126, 127), ethyl benzoate (Nos. 130, 131). The fact that there are two is not a fault of the theory; but, if there is a fault anywhere, it is in the large variations of specific gravity obtained by experimentalists. The raison d'être of these variations will appear later. It is only necessary to state here that similar variations occur in nearly all compounds of benzene If this statement contains an actual truth, then, of course, the majority of benzene compounds will be likely to be mixtures of the two forms. This is the explanation of benzyl iodide (No. 39) being given (774)—16·42—3275.

as

The same remark applies to several others of the foregoing compounds of benzene.

With regard to the two volumes found for OH, nothing can be said at present, except that the distinction between them will appear later.

In No 53, 4971 is the relative volume of O-CO-CH,, whilst in No. 54 the same figures represent the volume of CO-O-CH,; so that the volumes of these two different arrangements of atoms are the same. The same is true of 6613 and 82.55.

49'71, 66′13, 82-55, 98'97, and 115:39 are volumes of groups which differ by CH2, and therefore the difference between any two of them ought to be 16:42 or a multiple of 16:42, as it is.

It has been found necessary to begin by investigating the volumes of groups of elements, but later the relative volume of each atom in these groups will become evident.

There is already no doubt at all that perfect regularity exists at the temperature of 15° C., and it remains to be seen how much further this regularity goes, and to what conclusions it leads us.

(To be continued.)

NOTE ON AUGITE FROM VESUVIUS AND ETNA.

By HENRY S. WASHINGTON and H. E. MERWIN.

THE problem of the constitution of the pyroxenes that contain alumina and ferric oxide-the augites -is one of the most puzzling and, in some respects, one of the most important that are presented by the rock-forming minerals. In an effort to aid its solution, I have made during the last few years a number of analyses of typical augites from Italian volcanoes, in the lavas of which augite is one of the most constant and most characteristic minerals. The study of these is not yet complete, and several more analyses remain to be made. But having recently completed two analyses of augite from Vesuvius and Etna, of which Dr. H. E. Merwin has determined the optical and crystallographic data, it seems to be advisable to publish the results as a slight contribution toward our knowledge of this important group of minerals. This seems to be the more justified as, notwithstanding that the species was based first on the crystals from these two volcanoes, we have as yet no satisfactory or modern analyses of them.

Augite from Vesuvius. Vesuvius has long been noted for its pyroxenes. Beautiful diopsides are found in many of the ejected blocks of Somma, and loose crystals of augite are among the products of many of its eruptions. The crystals studied here were obtained from the bottom of the crater, in part by me in June, 1914, and in part by Dr. A. Malladra, Director of the Osservatorio Vesuviano, during the same spring. For his kindness in sending me the material for study I would express my sincere thanks.

Occurrence.—The crystals are found, either loose, and entirely or almost entirely free of scoria, as at many other volcanoes; or as phenocrysts in a highly vesicular leucite tephrite, which was being ejected in small amount from the orifice at the bottom of the funnel during my visit to it (A. Malladra, Rend. Acad. Sci. Napoli, Nov., Amer., 1915, xxvi., 375). 1914; Washington and Day, Bull. Geol. Soc.

The crystals are mostly of the usual, wellknown, simple forms, such as are figured by Dana ("System", 1892, p. 354, Figs. 16,17,18) and in most text-books of mineralogy. The faces present are a(100), b(010), m(110), and s(111). A small proportion are twinned, forming the common contact twins, with twinning plane a(100). They vary, in general, from 3 to 5 mm. in length (parallel to the vertical axis), though some attain lengths of I cm. or more. The thickness is from one-half to two-thirds of the length, and there is usually a slight tabular development parallel to a(100) The faces are fairly smooth and bright, much brighter than those of the Stromboli augites described in a previous paper (Kozu and Washington, Amer. Jour. Sci., 1918, xlv., 463), and the edges are sharp. There is but little scoria adherent to the loose crystals, but microscopical examination of the powdered material revealed the presence of small amounts of inclusions of glass and crystalline matter (magnetic, leucite, and feldspar).

Physical Data.-Of a dozen crystals studied, four had sets of faces that were sufficiently good for approximate measurements (by Merwin). These indicate the probability that crystallographically diopside does not represent augite. The measurements were as follows: mɅm (110) A (110) = 92°0′-93°57′; mean =

92°56'4 measurements.

S^S (111) ^ (111)=61°20'-59°50'; mean= 60°36' 8 measurements. For diopside the measurements are:mɅm=92°50′, s^ s = 59°11'. Measurements of and p four pyramid faces, s, gave values of 24°23'-25°5' and 34°1'-33°15', respectively, as compared with 25°7′ and 33°4' for diopside.

Speaking of the pyroxenes as a group, Dana (Dana, “System,”1892, 363) long ago pointed out : "It is noteworthy that the angles vary but little even for a wide variation in composition." While this is quite true, yet since that time, with more exact means of measurements and of chemical analysis, a more systematic study of the relations of the physical and chemical properties, and for other reasons, we are beginning to appreciate more than we did thirty years ago the probable importance of even small variations.

An optical examination showed that the Vesuvius augites studied are variable in composition The general colour is a slightly yellowish grey, and there is little indication of zonal structure. There is little if any pleochroism. The index 8 varies from 1700 to 1711. The extinction angle is large, as usual, about 45°, but no exact measurements were made, because of the variability in composition and the consequent indeterminateness of the data.

The specific gravity of the crystal fragments used for the analysis was found to be 3242 referred to water at 23°. This low result is probably to be ascribed to the presence of the glass inclusions.

Chemical composition. For my analysis some of the cleanest loose crystals were selected, and, in order to obtain sufficient material, to these were added crystals obtained from specimens of the scoria from about the orifice. Great care was taken to free the crystal fragments from adherent scoria, and the analysis was made on what was probably as pure material as could be obtained from this source. It was, however, not practicable to obtain material entirely free from the small inclusions of glass, &c., and the analysis, therefore, does not represent an entirely pure augite substance. In spite of this defect, however, it is thought best to publish it, as a slight contribution to our knowledge of the Vesuvian augites, and as illustrative of the dangers, in the form of included foreign matter, that may lurk in the chemical study of many minerals. The presence of the inclusions is also of interest in view of the very close correspondence in chemical composition between these augites and a pyroxenite published by Lacroix, to be mentioned later.

1. Augite, Crater of Vesuvius, June, 1914. Washington analyst. 2. Augite, Monte Somma. Doelter analyst. Tschermak's Petr. Mitth.", 1877, 283,

44 Min.

3. Augite, Vesuvius. Casoria, ref. Zs. Kryst., 1907, xlii., 881. 4. Pyroxenite, Monte Somma. Pisani analyst. Lacroix, C. R 1917, clxv, 209.

Earlier Analyses.-The earlier analyses of Vesuvian augites, collected by Dana, Hintze, and Doelter, and most completely by Zambonini (F. Zambonini, "Mineralogia Vesuviana, 1910, 151), very unsatisfactory, either because of their early dates, or because of their incompleteness. However, two of them, which seem to be somewhat less inferior than the others, are given in Table I.

While these older analyses show the general characters of augite, yet they all are seriously defective in that titanium dioxide and the alkalies are not determined in any of them, although it is clear from my analysis, and from our knowledge of augites elsewhere, that these constituents are present in distinctly appreciable amounts. The high alumina shown by them is due to the presence of titanium dioxide. Furthermore, the iron oxides are not separated in many of them. Lacroix has called attention (A. Lacroix, C. R., 1917, clxv., 211) to these serious defects in all the existing analyses of pyroxenes of Vesuvius, and I can only join with him in urging the need for better analyses of this mineral group from Vesuvius and from other localities, and incidentally, call attention to the genera] inferiority of the great majority of the analyses of pyroxenes, especially as regards the fundamental points of selection of pure material, and accuracy and completeness of the analyses.

The publication of analyses of such inferior quality is to be deplored, as leading possibly to seriously incorrect generalisations at the hands of those who accept blindly and without critical judgment any analysis that is offered them. One of the striking features in the study of the chemistry of minerals and rocks is the complacency with which such inferior work is accepted and published. Much of it is based on impure material, often not ascertainedly so, carried out by inexperienced analysts, by poor methods, or with impure reagents; and yet it is accepted in good faith by both analyst and author. This state of affairs has done much-much more than is generally thought-to hinder the progress of our knowledge of the chemistry of minerals.

Comparison with pyroxenite. It is not necessary here to discuss my analysis of the Vesuvius augite, partly because of its being based on impure material, and partly because it will be discussed later, when the series of Italian augites is more nearly complete. Attention must, however, be called to the very remarkable correspondence between it and an analysis by Pisani of a pyroxenite of Monte Somma, published by Lacroix, which Lacroix does is given in column 4 of Table I. not describe this rock in detail, but it would appear to be holocrystalline and composed almost It is a somewhat noteentirely of pyroxene. worthy example of the possibility of diverse crystallisation of a part of a magma, either as a monomineralic or almost monomineralic, granular rock, or as well-formed crystals of a definite mineral.

Lacroix mentions and gives analyses of several types of the pyroxenite, all of which are more or less closely related chemically. It occurs, according to him (A. Lacroix, C. R. 1917, clxv., 205), as homoegogenic rocks, that is, "granular forms, not only of the flows, but also of the differentiated portions of the same magma which have not necessarily reached the surface." Such homoeogenic rocks are assumedly of abyssal origin, and, if the general theories of gravitative adjustment of Daly and Bowen are correct, they would be expected to have come up, or been carried up, as broken-off blocks, from very deep down in the volcanic mass. My augite crystals, on the other hand, occur, as has been said, in the light scorias that form the uppermost scum or froth of the ascending magma.

18

This would indicate that, in this case at least, separation by gravity has not been carried to completeness. That this is also true elsewhere is indicated by the occurrence of such augite crystals (almost always of the same crystal form) at other volcanoes, such as Stromboli, Etna, and the Alban volcano. Indeed, they are rather common many volcanoes, and similarly crystals of cossyrite and kaersutite (sodic hornblende) are met with as such loose crystals at Panelleria and Linosa, to speak only of Italian volcanoes.

at

But the incompleteness of such a separative process is not to be wondered at, considering the convection currents in, and the presumably violent movements of, the upward-welling mass of magma, as well as the presence of gas, whose bubbles would act like those in a glass of champagne to keep up a dry raisin, which would otherwise sink ("Forsan et haec olim meminisse juvabit”).

The interesting point is that, with portions of the magma of almost identical composition, we get, in the one case, a typically granular rock, and in the other, well-formed, loose crystals. We have, unfortunately, no detailed petrographical description of Lacroix's pyroxenites. Of some of them he says (p. 210) that they are composed of "a little leucite filling the interspaces of plates of biotite which surround automorphic crystals of augite or inclose them poikilitically." Of the most pyroxenic type, that of which an analysis has been cited, nothing is said as to the form of the augites; but their being spoken of as granular ("grenues") leads one to think that the augites are xenomorphic. We know many pyroxenites from elsewhere of this granitoid type of texture and, so far as my experience of them goes, they do not show evidence of being built around automorphic and euhedral crystal cores; though conceivably evidence of such an origin may well have been obliterated in the process of growth, if this were not zonal.

It will be evident that pyroxenites of the first type of Lacroix, with automorphic augites, would be quite in harmony with Bowen's theory of the settling of the heavy crystals in a magma (N. L. Bowen, Amer. Jour. of Sci., 1915, xxxix., 175). (The sinking of crystals of feldspar and their accumulation at the bottom of flows of obsidian were observed by Von Buch (Geogn. Beschr. Canar. Ins., 1825, 229), who mentions experiments made by a M. de Drée, in which feldspar crystals settled to the bottom of a crucible. The matter is discussed by C. Darwin, about 1844 (“Geological Observations," 2nd. ed., 1891, 132-140), who attempts thus to account for the differentiation of trachyte and basalt). Bowen studied the sinking of olivine and pyroxene crystals, and the rising of those of tridymite, in artificial melts, and the striking way in which the first two sank and the third rose was sufficient proof of the actuality of the phenomenon and the relative densities of crystal and liquid. So far as I know, we have few data, at least exact data, on the densities of liquid lavas, but the point arises as to whether the augite crystals are really heavier than the liquid in which they occurred.

The density of the augite crystals was determined as 3242 at 23°. The average density of the solid leucite tephrite of Vesuvius (cf. Roth, Abh. Berl. Akad. Wiss., 1877, 13; and Zirkel, Lehrb. Petrog., 1894, iii., 19. Roth gives the

average as 277) may be taken as about 28, while vom Rath (vom Rath, Z. deutsch geol. Ges., 1873, XXV., 240) gives the values 2.512 and 2592 as the densities of the glassy crusts of Vesuvian bombs of 1872, and Lagorio (Lagorio, Tscherm ̧ Min. petr. Mitth., 1887, viii., 475) 2319 as that of a Vesuvius obsidian. We may therefore provisionally accept a density of about 25 for the Vesuvius glass. As to the liquid lava, we have no data; but, assuming a density of 28 for the solid lava, we may conclude from the discussion of Daly (R. A. Daly, Amer. Jour. Sci., 1903, xv., 277) based on Mellard Reade's and Barus' data as to expansion, that the molten lava would have a density of about 2:35. This does not take into account the presence of dissolved gases, which would unquestionably lower the density, and at the same time decrease the viscosity, very materially. It is clearly evident, therefore, that augite crystals, placed in such a leucite tephrite magma, would be much more dense than the magma, and would tend to sink, though the actual sinking of many of them would be more or less prevented by movements in the liquid, and by the possible presence of attached gas bubbles in the upper portions of the mass. Anyone who has made mineral separations with heavy liquids will appreciate the possibilities of disturbance of a "theoretically" perfect separation, adherent particles of the lighter minerals here replacing the gas bubbles of the magma,

But the occurrence of masses of rock of granitic texture, without euhedral crystals, or crystals formed freely in the body of the liquid, of the same composition as such crystals formed in what must have been a very similar magma and at the same volcano, seems to demand the recognition of some other factor than gravity, or at least one in addition to that of gravity.

This is not the place to enter into a discussion of the various kinds or causes of differentiation that have been suggested, but I must recall the case of Shonkin Sag and the explanation of its differentiation by fractional crystallisation advanced by the late Prof. Pirsson, which, it seems

to

me, Daly has not adequately met by an appeal to gravitative differentiation (L. V. Pirrson, Amer. Jour. Sci., 1901, xi., 12; U.S. Geol. Survey, Bull. 237, 1905, 188. Cf. Daly, "Igneous Rocks and their Origin," 1914, 223, 238).

Pirrson

and I held much the same views on these matters, and I feel inclined to revive a theory put forward many years ago (Washington, Bull. Geol. Soc. Amer., 1900, xi., 409, 414; Jour. Geol., 1901, ix., 663), chiefly to account for the different types of laccolithic differentiation. This is based on fractional crystallisation, perhaps aided by convection currents, as Pirrson supposed, the crystallisation beginning at the rough walls, and the crystals of this portion (in the present case monomineralic) interfering with each other so as to produce a granitoid textured rock. Crystallisation of free floating crystals (therefore euhedral) in the magma could, and probably would, also go on simultaneously. The process is analogous to the slow freezing of a bottle of salt solution, which begins at the walls, so that clear ice forms above, at the sides, and at the bottom, leaving finally a central core of highly concentrated solution. With the more complex rock magmas the process would be conceivably more complex than this, but the

same general principles would seem to apply. Unquestionably, the influence of gravity might or would be felt, especially on the loose floating crystals, but this would probably have less or no effect on the wall accumulations. The process is analogous to Daly's chilled border concept, but differs from this in that, according to Pirrson's and my hypothesis, the border crystallisation product does not represent the original magma, as conceived by Daly, but would be an “extreme pole of differentiation."

(To be continued.)

BRITISH INDUSTRIES FAIR, 1921.

FEBRUARY 21-MARCH 4.

IN a few days' time the British Industries Fair, London, for 1921, will be opening its doors at the White City to the buyers of the world. This will be the seventh London Fair, and promises to surpass its predecessor even as that in its turn added to the roll of success. It is estimated that there will be some 3 miles of stands displaying British goods at the White City. Since its inception in 1915, the record of the British Industries Fair has been one of continuous growth in scope, utility, and reputation. Started as a means of promoting the manufacture in the United Kingdom of articles previously made in enemy countries, the Fair made so instant an appeal and received such warm support from its exhibitors, that it has never looked back, and is now established in a predominant position among the great trade fairs of the world. The secret of this success is not far to seck; the British Industries Fair is a business exhibition for business men. Producing trades are carefully grouped for the convenience of the inspecting buyer, and these groups are again split up into sections and so housed and exhibited as to facilitate to the utmost a rapid and thorough survey of British production in any given line. The foreign buyer is invited by the Department of Overseas Trade, and invitations only extended to bona fide firms and representatives, thus enabling both buyer and seller to conduct their business unhampered by a crowd of sightseers. Participation in the Fair, limited to manufacturers in specified British trades, is both cheap and simple, offering equal opportunities to both large and small firms. This year's exhibitors cover both categories, and form the most representative body of British manufacturers ever assembled. Their names alone are a guarantee of the quality of the goods to be displayed and their keenness to exhibit is shown by the fact that the available space in every section of the Fair has been applied for several times over.

The goods to be displayed in the London Section include books, cutlery, silver and electroplate, jewellery, watches, and clocks, hard haberdashery, glassware of all descriptions, china, earthenware and stoneware, paper, stationery and stationer's sundries, printing, fancy goods, including travelling requisites and tobacconists' sundries, medical and surgical instruments and appliances, leather for the fancy goods, bookbinding, and upholstery trades, brushes and brooms, toys and games, sports' goods, scientific

[February 18, 1921

and optical instruments, spectacle ware and opticians' supplies, photographic and cinematograph apparatus and requisites, drugs and druggists' sundries, musical instruments, furniture other than metal, basketware.

The Birmingham Fair also opens on Feb. 21, at the Castle Bromwich Aerodrome. The oversea visitor will have the opportunity to inspect some 20 sections covering the trades for which that city is world-famous. Every type of fitting for lighting and cooking, and a wide range of hardware, including household ironmongery will be on display, together with metal furniture and saddlery, indiarubber goods and motor accessories. In fact, almost every branch of the British metal industry will be represented.

The exhibits at the well-known Kelvin Hall Glasgow, will include textiles of all sorts, readymade clothing, hats, boots, carpets, foodstuffs, chemicals, and dyes. This Fair opens and closes a week later than the London and Birmingham Sections

So much for the home end of the Fair. A good show is guaranteed; what of the use to which it will be put? Never has the foreign buyer had a more favourable opportunity for purchasing in our markets. The tremendous demand prevailing in the home market early last year has fallen to below normal, contracts have had to be cancelled or curtailed, with the result that the British manufacturer has ample stock in hand to meet new orders. No opportunity has been missed by the Department of Overseas Trade and the organisers of the Birmingham and Glasgow Sections of bringing those favourable conditions to the notice of the foreign buyer.

With the financial support of the exhibitors, the Department of Overseas Trade has conducted a wide publicity campaign in the oversea press, in addition to the normal propaganda activities. Reports so far received promise excellent results. Invitations have been issued to some 60,000 overseas buyers of standing, and the same number of illustrated booklets, translated into eight languages, have been issued all over the world. Liberal use has also been made of showcards with the assistance of overseas banks, shipping companies and the Consular Diplomatic Officers of the Department in all parts of the world. Excellent reports as to the number of visiting buyers have been received from Scandinavia, where special conducted tours during the Fair are being arranged. From the United States, also, the prospects of a large number of visitors are favourable. Switzerland, Finland, Canada, and Italy are among countries where interest in the Fair is also reported as being considerable. Many committees, both official and unofficial, in this country are studying the question of the entertainment of the oversea visitor. During the period of the Fair, it is hoped that official foreign commercial missions will visit this country as guests of the British Government.

The White City not only provides the exceptional floor space necessary for the British Industries Fair (35,000,000 cubic feet are available), but has the merit of being easily accessible. The exhibition buildings are grouped between five railway stations, all giving direct access. Twenty minutes by taxi will cover the journey from all parts of the West End.

18

THE THEORY OF RELATIVITY.

No scientific subject has excited so much discussion in recent years as the Principle of Relativity developed by Lorentz, Einstein, and Minkowski. Since the work of Faraday and Clerk Maxwell, the existence of an all-pervading æther has been an accepted doctrine of physical science. The æther was conceived as stationary, yet all testslike that of the classical experiment of Michelson and Morley-failed to detect the movement of the earth through it. FitzGerald suggested that the dimensions of the apparatus were affected by the movement. On the theory of the electromagnetic constitution of matter, Larmor and Lorentz

worked out mathematically the consequences of this view. The conclusion was reached that no experiments could ever reveal absolute motion. Einstein showed that remarkable consequences as to the time and space followed from this proposition, necessitating a new mental picture of the physical universe. The details of this conception constitute his presentation of the Theory of Relativity.

Many physicists find it difficult to abandon the idea of the existence of the æther as they have come to think of it, and do not consider such a revolutionary change of thought is necessary as is involved in the complete acceptance of the principle. The different aspects of the theory are described in the important articles published in the special issue of Nature on February 17. The contributions constitute the most authoritative scientific statemen on relativity from different points of view yet published, and the number will be of permanent value.

The articles will include the following :"A Brief Outline of the Development of the Theory of Relativity" by Prof. A. Einstein. "The Michelson-Morley Experiment and the Dimensions of Moving Bodies," by Prof. H. A. Lorentz, For. Mem. R. S

"Electricity and Gravitation," by Prof. H. Weyl. "Theory and Experiment in Relativity," by Dr. Norman R. Campbell.

"The Metaphysical Aspects of Relativity," by Prof. H. Wildon Carr.

"Relativity and the Motion of Mercury's Perihelion," by Dr. A. C. D. Crommelin. "Relativity: the Growth of an Idea," by E. Cunningham.

"Relativity and the Eclipse Observations of May, 1919," By Sir Frank Dyson, F.R.S.

"The Relativity of Time," by Prof. A. S. Eddington, F.R.S.

"The General Physical Theory of Relativity," by J. H. Jeans, Sec. R.S.

"The Geometrisation of Physics, and its Supposed Basis on the Michelson-Morley Experiment," by Sir Oliver Lodge, F.R.S.

"Non-Euclidean Geometries," by Prof. G. B. Matthews, F.R.S.

"On the Displacement of Solar Lines," By Dr. C. E. St. John.

"The Relation between Geometry and Einstein's Theory of Gravitation," by Dorothy Wrinch and Dr. Harold Jeffreys.

Bibliography of Books and Pamphlets on Relativity.

CORRESPONDENCE.

DYESTUFFS (IMPORT REGULATION) ACT, 1920.

To the Editor of the Chemical News. SIR, The Council of the Institute of Chemistry have addressed a letter to the Board of Trade, enquiring whether licenses would be necessary under the Dyestuffs (Import Regulation) Act, 1920, for the import of small quantities of organic chemicals (including intermediate products used in the manufacture of dyestuffs, &c.), required solely for research purposes. I enclose herewith a copy of the reply received.-I am, &c.,

[Copy]

RICHARD B. PILCHER.

(Registrar and Secretary).

Board of Trade

(Industries and Manufactures Department 8th February, 1921.

SIR, With further reference to your letter of the 28th January, regarding the Dyestuffs (Import Regulation) Act, 1920, I am directed by the Board of Trade to state that, whilst it is not possible to regard small quantities of organic intermediate products which may be required for research purposes as being outside the scope of the Act, the Board will be prepared to issue general licenses for the importation of such products to approved research institutions, covering periods of three months and limited only as to total quantities. This procedure will obviate the necessity for separate applications for a large number of small items, but it will be a condition of the issue of any general license that a detailed return shall be furnished at the end of the three months during which the license is in operation, of the quantities of each product actually imported under it.—I am, Sir, your obedient servant,

(Signed) PERCY ASHLEY. The Registrar & Secretary, Institute of Chemistry of Great Britain & Ireland, 30, Russell Square, W.C.1.