July 7, 1904] 



NATURE 



and chlorine atoms become respectively combined with 

 water. With sufficient water present the original union 

 between the sodium and chlorine atoms will become entirely 

 severed, the Faraday bundle starting with its positive 

 extremity on the sodium atom will terminate at its negative 

 end by means oj a plurality of strands on a number of 

 water molecules, and similarly the Faraday bundle eman- 

 ating by its negative extremity from the chlorine atom will 

 terminate at its positive end in a plurality of strands also 

 on a number of water molecules. In such a solution we 

 should thus have independence of the sodium and chlorine 

 atoms, or the phenomenon of ionisation. In such a solu- 

 tion, moreover, the union between sodium and chlorine 

 would be entirely abolished through the complete diversion 

 of the strands of the Faraday bundle formerly uniting them, 

 whilst the union between the oxygen and hydrogen of the 

 water molecules would be but slightly weakened owing to 

 only a small fraction of the total number of strands in the 

 bundles uniting the oxygen and hydrogen in each molecule 

 being diverted by the sodium and the chlorine. The 

 dissociation into its ions of an electrolyte on solution in 

 water would thus be the consequence of the antecedent 

 hydration of the ions. 



Some of the colour changes attending the attachment of 

 water of crystallisation may be interpreted in the same 

 way. 1 hus anhydrous copper sulphate is colourless, whilst 

 the crystallised salt containing five molecules of water is 

 blue. The direct union of the copper atom by means of two 

 Faraday bundles with the SO, -group leads to the produc- 

 tion of a colourless compound, whilst by the diversion of 

 the strands of these bundles, through the attachment of 

 five molecules of water, the copper atom and the SOj-group 

 become severed, and the blue colour characteristic of the 

 copper ion makes its appearance. 



.According to this view solution should always be attended 

 by the weakening of the union between at least one pair 

 of bonds in the molecule of the solute owing to the 

 diversion of at any rate some strands of the bundle or 

 bundles, and such loosening is betrayed in the greater 

 chemical reactivity of substances in solution. 



Similarly in catalytic phenomena, the catalytic agent may 

 be regarded as diverting some of the constituent strands 

 of bundles, and the action of water in effecting ionisation, 

 i.e. complete diversion of bundles, would thus appear as an 

 extreme case of catalysis, leading to such an acceler- 

 ation of the velocity of reaction between electrolytes that 

 reactions between ionised electrolytes are practically 

 instantaneous. 



It is needless to say that this is merely a preliminary 

 and very imperfect attempt to apply the electronic theory 

 to a few of the most familiar and important chemical 

 phenomena. Sir Oliver Lodge's suggestion with regard 

 to the electrical interpretation of valency and bonds is 

 indeed so luminous and stimulating that it should provoke 

 the careful review of chemical facts by the light of this 

 new conception of the possibility of an indefinite number 

 of different grades of chemical union, of which the union 

 by chemical bond, hitherto the only one generally recog- 

 nised, is to be regarded merely as an extreme case. 



Birmingham, June 27. Percy F. FR.'iNKLAND. 



Science in the Common Examination for Entrance to 

 Public Schools. 



Is the interests of education, may I ask you to find room 

 in your columns for the enclosed copy of the science paper 

 recently set in the above examination? The average age 

 of the candidates may be taken as about thirteen years. 

 Comment is almost superfluous. The effect, whether in- 

 tentional or not on the part of those who set the questions, 

 of such an examination paper must be to discourage science 

 in the preparatory schools. No boy of thirteen years of 

 age could or should be expected to answer more than a very 

 small portion of so advanced a paper. If headmasters of 

 pi eparatory schools are led to imagine that this is the 

 kind of thing that is expected of their pupils, in very despair 

 they will be forced to abandon science entirely, and fall 

 back upon its alternative in this examination — Latin verse. 



This common examination has now been held for the 

 first time, and it is important that an emphatic protest 



NO. 1 8 ID, VOL. 70] 



should be raised without delay. If the science paper is 

 allowed to be of this unreasonable character, the subject 

 win receive a set-back that will go far towards undoing 

 all that has been tardily achieved during the last twenty 

 years in regard to scientific teaching in our public schools. 



0SW.^LD H. L.«TER. 



Charterhouse, Godalming, July 2. 



June 29, 1904. — Seventh Paper. 

 (."Mternative with Latin Verse.) 



COMMON EXAMINATION FOR ENTRANCE TO 

 PUBLIC SCHOOLS. 



Science. — (One hour.) 



I. — Physics. 



(i) \ weight hangs by two strings each making an angle 



of 60° with the vertical. Show that the tension of each 



string is equal to the weight. . 



(2) A uniform rod 10 feet long and weighing 5 lb. is 

 pivoted 3 feet from one end. A weight of 50 lb. is hung 

 on the end nearer to the pivot. Find what weight must 

 be hung on the opposite end to balance the rod. 



(3) Gravity is often measured by the number 32. Ex- 

 plain this. A body is throwm up with a velocity of 48 f. s 

 In what time will it lose its velocity? In what time will 

 it return to the hand? How high will it go.-- 



(4) A rectangular vessel on a square base is filled with 

 water. Find the relation between the height of the vessel 

 and a side of the base in order that the fluid pressure on 

 one vertical face may equal that on the base. 



II. — Botany. 



(1) Enumerate the floral whorls from outside inwards. 

 Explain what is meant by cohesion and adhesion among 

 floral organs. Make a careful drawing of the section 

 through a flower in which petals and stamens adhere to the 

 calyx tube. Name a flower in which you have observed 

 this structure. , , . »o 



(2) A potato is often spoken of as a root. Is this correct? 

 Give reasons. Name three other cases in which a similar 

 error is made, explaining the real nature of the organ ir» 

 question. ■ ■ »u u 



(3) Draw sections shown in cutting lengthwise through 

 a bean (or acorn) and a grain of barley (or date stone). 

 What difference would be observed during their early 

 growth? Of what great divisions of plants are these 

 characteristic respectively? „ , - o 



(4) What plants would you expect to find in flower m a 

 damp wood on a clay soil in April? Describe one or more 

 of them. 



An Early Mercury Pump. 



It may interest some of your readers to know that as- 

 early as '1820 an air pump was described depending on the 

 formation of a Torricellian vacuum, and therefore on the 

 same principle as Geissler's and its successors.^ The paper 

 is by M. Fafchamps— " Description d'une machine pneuma- 

 tique a I'aide de laquelle on opfere le vide sans le secours d« 

 la pompe " {.innales generates des Sciences physiques, 

 Bruxelles, vol. vi., 1820, pp. 101-2). 



A vertical tube standing in a trough is provided with a. 

 stop-cock near its upper end. The tube above the s op- 

 cock has a reservoir at the top, and on each side is a stop- 

 cock, one connected with the vessel to be exhausted and the 

 other to a large funnel. The upper end of the reservoir 

 is also provided with a stop-cock. To work the machine 

 the reservoir is first filled with mercury or some other liquid, 

 which is introduced through the funnel, the air being ex- 

 pelled through the stop-cock at the top of the reservoir. 

 When filled with liquid the stop-cock of the reservoir is 

 closed and communication with the funnel is cut oft. ine 

 stop-cock on the tube is now opened, when a Torricellian 

 vacuum is produced in the reservoir; on opening the cock 

 connected with the receiver air is withdrawn, and so on. 



The author remarks that if mercury is used, the vertical 

 tube must be 758 mm. long: if water, the tube must be 

 more than 10 metres, but the length of the tube may 

 be reduced bv diminishing the atmospheric pressure on the 



