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also t h a t free use is made of the theorem of Le Chatelier and of the electrolytic dissociation theory. It is fairly evident t h a t more and more physical chemistry is being introduced in the elementary courses both in Belgium and in America. On p. 616, the author apparently considers lead acetate purely a s a catalytic agent in the conversion of lead into white lead by the Dutch process. ilccording to this view, the white lead is formed by the action of carbon dioxide upon lead hydroxide. If this is the case, i t would account for the excellent properties of t h e white lead made b y this process; but i t ought also b e very easy t o duplicate the results by a quicker method. TVilder D. Baizcrojt Ueber die Schichtungen bei Diffusionen. E i n e Vori~iitersuchzilzg. B y R a p h a e l Ed, Liescgnng. 14 X 22 c m ; pp. ,jj. Leipzig: II~illieliiz Eizgelmaiin, 1907. Price: p a p e r , 1.60 nzarks.-The author found great difficulty in repeating his earlier experiments on the ring-shaped deposits of silver chromate formed when silver nitrate is allowed to diffuse into a gelatine film containing potassium bichromate. A long series of experiments finally brought out the fact that the chief variable Jvas the quality of the gelatine. If the gelatine film nere alloived to age for several days, marked differences in the arrangement of the rings were obtained. It is n o t primarily a question of the viscosity of the gelatine. b u t depends rather on the hydrolytic decomposition of the gelatine. Using the figures a s a method of testing, i t n a s found t h a t the gelatine rvas not the same a s a commercial sample of glutine. W i l d e r D . Ba ncrojt Trait6 complet d' Analyse chimique appIiqi& a m Esseis indusfriels. B y J . Post aizd B . .Yeihiizaizii. D e i i r i h c bditioit j r a n p i s e enti2rwtent rejoitdne. Tradicife d'lipr6s la troisi2ine tditioia nllenzaizdc et aiLgiiaentc'e de nonzbrt.user a d d i tions pav L . Gauticv. Toirie pvcmicr, preinicr jasciczile. Prix, 6 jr, 50.--The complete work is to consist of t v o volumes, each having four parts. The present number is the first of volume one. I t deals with water, combustibles, pyrometry, a n d gas. The chapter on pyrometry is the one which \Till appeal the most to the physical chemist and is a n excellent one. I n the pages on the optical pyrometers we find a discussion of the instruments of Le Chatelier, IVanner, Fkry, Holborn and h u r l b a u m (Morse patent), Il.ildcr D . Baizcrojt
Les Rayons Cathodiques. Bj,P. \'illard. (C'ollcctioii S c z e n t i a . ) U c ~ii idiize L(ilitioi2. 13 x 2 0 cm; pp. IO;.. P a r i s : Gaiitiiicr-I'illars, 1908. ~ v i r c :l i n e n , z jrancs.-The
subject is treated under the headings: apparatus; electrical phenomena in rarefied gases; cathodic emission ; electrification of the glass tube ; properties of cathode rays; X-rays; electrification of cathode rays; electrostatic effects; action of a magnetic field on cathode rays; velocity of cathode rays; heterogeneity of cathode rays; chemical action of cathode rays; diverse phenomena ; formation of cathode rays. The last two pages of the book are devoted to a discussion of the nature of radiant matter. "In the first edition of this book we supposed that the cathodic coqiuscles were electrified particles of hydrogen. --It that time electricity was considered a s inseparable from matter and this hypothesis therefore seemed almost necessary, especially as i t explained perfectly the reducing action of the rays and the constant presence of hydrogen a t the cathode.
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"The remarkable work of J . J . Thomson and N a x Abraham has shown t h a t the presence of a ponderable carrier for electricity is not necessary and t h a t the laws of electricity are sufficient to explain the chief properties of the cathode rays. Returning to a n old hypothesis we assume the existence of electric fluids and, by analogy with ordinary matter, we suppose them formed of atoms of electricity, or electrons, having the absolute value of 1 . 3 X IO-'^ coulonib, which is equal to the charge carried by a n atom of hydrogen during electrolysis. Every electrical charge would therefore he composed of a whole number of these elementary indi\-isible masses and would constitute a n exact multiple of the unit charge just mentioned. According to this hypothesis the cathode corpiiscles are atonis of negatit-e electricity, in other words negative electrons. "The inertia of the corpuscles, shown by the form of the trajectories in a field, is to be explained its a phenomenon of self-induction: an electron in motion is equivalent to a current and produces around i t a magnetic field, in other words localized energy, the value of which in each space-element is proportional to the vnlume of the element and to the square of the field. The creation of this energy, I'. e . , the setting the electron in motion, necessarily requires a certain expenditure oi work just as is the case when any ponderable object is set in motion. \illen the motion is once estahlished and provided the velocity is constant, the field prodiiced is invariahle and moves with the electron. N o expenditure of work is then necessary to maintain the velocity. "If one stops the electron, the field formed by its displacement \vi11 disappear and the energy which this field represents will become free and will tend t o prevent the stopping. This energy thus restored is equal to that acquired when the electron was set in motion and is proportional to the square of the field, in other words to the current, and consequently to the square of the velocity just as in the case of the kinetic energy of any material substance. "These characteristics are precisely those of all mechanical mass and i t therefore seems possible to explain ordinary inertia by assuming t h a t matter consists solely of electrons. "This electromagnetic inertia 1i:is one remarkable peculiarity: the mass of an electron increases with the velocity and becomes infinite for the velocity of light. This increase is not appreciable for so-called mrcizenicul velocities. I t becomes important only as we reach 80 percent of the velocity of light. I t has been possible to verify directly this apparent increase in mass by means of measurements niade on the ;? rays of radium, which are true cathode rays but possessing enormous velocities even exceeding the value mentioned. "The mechanical properties of cathode rays are thus explained in a most sitriple \Yay. The case of light sho\vs us t h a t it is possible to account for the phenomena of reduction without falling back on hydrogen. Severtheless there are tivo difficulties. The ;3 rays of radium color glass and crystal violet and so do the X-rays.' The cathode rays from a Crookes tuhe reduce crystal and it seems difficult t o attrihute this difterence in action merely t o a difference in velocity. "The other dificulty is that the characteristic ratio e/m, of the electric By oxidation of the manganese. "
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atom ought to be constant and to appear in all phenomena where we are concerned directly with electrons. a matter of fact, i t varies from 1.865 X 107 (cathode rays) to 3.j34 X 1 0 7 (Zeenian effect) and even reaches the value of 1.656 X 1oS in the crystalline absorption. These discrepancies cannot be explained as due to differences in velocity for these could only increase the value of m and diminish t h a t of the ratio' e l m "In spite of these anomalies, the electromagnetic theory of the cathodic pheiioniena constitutes a marked advance, the greatest that has been made in this branch of physics since the work of Sir IT., Crookes." * Pellat has recently suggested a veri- simple explanation of these variations in e / ? n (Comptes rendus, 145,6 7 3 (1907)). Il'ilder 13.I i a ? z c r ~ j f Recherches theoriques et experimentales sur la Constitution des Spectres ultraviolets d'Etincelles oscillantes Lij' EiLgbne .YPczdcPcr. 2.j X a8 cm; p p . azo. Paris: A . Hermatin, 1903. Pyice: paper> 1 2 jmncs.-This volume colitains a n account of work begun in 1901. The author summarizes his conclusions a s follows: "The object of this investigation was to study the efiect of self-induction on the oscillating discharge with reference to the changes produced in the extreme ultra-violet portion ( i = z;oo-rmo Angstrom units) of the spectra of the metals forming the electrodes b e t w e n which pass the sparks coming from the discharge of a condenser. At every step there were so many experimental difficulties in the spectrographic study of this invisible region of the spectrum t h a t i t has been necessary t o devote a portion of this investigation to the theory of spectroscopic instruments h s e d on physical optics, a theory not very familiar t o spectroscopists, yet which throws a clear light on a number of apparently obscure points concerning the chuice and action of a spectroscopic instrument. d s a result of setting forth this theory as doctrine, it is hoped that people will finally give u p completely the old views, based on geometrical optics, which are entirely insufficient to give a definite account of the exact way in which a spectroscopic instrument acts. "11-e may sun1 up, as follows, our results on the effect of self-induction on the extreme ultra-violet portion of the spark spectra: I . Self-induction has a very powerful effect in the extreme ultra-violet region of the spark spectra of the metals we have studied: TI, P b , Bi, Sn,Sb, Cu, -Ig,Ti, Fe. 2 . The different ultra-violet lines of the metals just mentioned can be divided into three groups with reference to the variation of intensity when there is an increase of self-induction in the discharging circuit. The first-class includes those lines which weaken very rapidly with increasing self-induction. The second class includes those lines which only weaken gradually as the selfinduction increases. The third class includes the lines whose intensities pass through maxinia and minima as the self-induction of the circuit increases. This entirely natural classification of the lines was proposed by Hernsalech for the visible region of the spark spectra. I t is also valuable for the ultra-violet portion of the spectrum. 3. These three classes of lines may exist separately in the spectra studied.
