2/2 



NA TURE 



[January i8, 1894 



showed that, viewed in its general aspect, the Chalk Period 

 hears evidence of the almost continuous gain of elevation over 

 depression influence. According to his researches, the Upper 

 Greensand is the expression of coast-line conditions, the currents 

 transporting shore material being sufficiently strong to make 

 their influence felt over 150 miles from land. The chloritic 

 marl probably represents the denuding effect of the advancing 

 sea opon the sinking land. The chalk marl and grey chalk 

 seen; to have been deposited in areas of gradual subsidence ; j 

 judging from the change in the Foraminifera, the gradual re- 

 duciion in size and quantity of quartz and glauconitic grains, 

 and the absolute disappearance of heavy minerals (zircons, &c. ) 

 in the higher zones of the Lower Chalk. The great purity of 

 the chalk in the Tercbratulina gracilis zone, and the almost 

 entire absence of a heavy residue, indicates that the maximum 

 depression for the Middle Chalk period very probably occurred 

 about the time of the laying down of its central beds. From 

 this zone onwards the chalk becomes more and more marly, 

 passing finally into the condition of the chalk rock, that is, a 

 truly nodular bed. The reappearance of quartz and glauconite i 

 grains, and heavy minerals (Tourmaline, Augite, and Horn- 

 blende), all point to this rock as having been formed during a 

 period of elevation. The zones of the Upper Chalk show 

 typically the continuation of great depression, for the flints 

 gradually become reduced in size, and pass through various 

 changes of shape, that is to say, from irregular to zoned, and 

 finally to the tabular form. 



An important experimental research on the " Decomposition 

 of Liquids by Contact with Powered Silica, " was described by 

 Dr. G. Gore at a recent meeting of the Birmingham Piiilosoph- 

 ical Society. The method of experiment employed was simply 

 to take 25 centims. of a solution of an acid, salt, or alkali, of 

 known composition, which had no chemical action upon pure 

 precipitated silica (or other suitable insoluble powder), in a 

 stoppered bottle ; add to it 50 grains of the powder, thoroughly 

 agitate the mixture, set it aside, usually about sixteen hours, and 

 analyse the clear liquid portion. This enabled the chemical 

 composition of the film of liquid wfhich adhered to the powder 

 to be approximately ascertained, and the influence of surface 

 tension upon such composition to be examined. The experi- 

 ments show that the chemical composition of films of liquid 

 adhering to solids may be approximately ascertained by this 

 method. They further show that the power of abstracting dis- 

 solved substances from liquids is a common property of finely 

 divided solid bodies, and that the amount abstracted varies with 

 the kind of powder employed ; the degree of fineness of the 

 powder, and consequently the amount of its surface ; the kind 

 of dissolved substance ; the proportion of powder to dissolved 

 substance ; the kind of solvent ; the proportion of solvent to 

 powder ; the proportion of dissolved substance to solvent : and, 

 in a small degree, with the temperature. The union takes place 

 quickly, and a long period of time has but little inflaence. 

 Fmely precipitated silica possesses the property in the greatest 

 degree, and alkaline substances are the most affected ; with very 

 dvlule alkaline solutions more than 80 per cent, of the dissolved 

 substance was abstracted by the silica. The results appear to 

 throw some light upon the purification of water by filtration 

 through the earth and upon agriculture, and to show that the 

 alkaline constituents of soils are retained much more by the 

 silica than by the alumina. The effects of silica upon weak 

 solutions of potassium cyanide indicate that the great loss of the 

 latter substance in the commercial process of extracting gold and 

 silver from powdered qaartz is largely due to the " adhesion " of 

 that salt to the silica. And the results obtained with silica and 

 a very weak solution of iodine indicate a possible method of ex. 

 tracting the latter substance from solutions, and the recovery of 

 NO. 1264, VOL, 49] 



the iodine from the silica by distillation. The research brings 

 more closely together the sul>jects o( physic-; and chemistry. 



The Analele of the Roumanian Meteorological Institute, 

 vol. vii., contains an account of a glazed frost, or smooth coat- 

 ing of ice, which occurred on November 11 and 12 last over a 

 very large tract of country, and caused much damage to trees and 

 telegraph lines ; some of the trees had not only their boughs, 

 but even their trunks broken by the weight of the deposit. Dr. 

 Hepites states that in this case the cause of the formation of 

 the glazed-frost was not that the rain fell upon objects at a 

 temperature below zero, as the phenomenon has sometimes been 

 explained, but that it is probable that the drops of rain were 

 in a state of superfusion, and became frozen on touching the 

 objects on which they fell. When the glazed-frost commenced, 

 the temperature on the ground was Z^^'S- ^^ ^^^ neighbour- 

 hood of Bacharest the telegraph wires were coated with ice an 

 inch in diameter, and were thickly studded with stalactites of 

 ice. The weight of this coating over the length of a metre of 

 the wire was thirteen times as heavy as the wire itself. 



The numerous attempts which are at the present time being 

 made to utilise the energy which runs to waste wherever there 

 is a waterfall, and which have lately had considerable public 

 attention drawn to them on account of the publication of Prof. 

 Forbes' paper on the utilisation of the Niagara Falls, have 

 received an interesting addition in the attempt that is being 

 made on the canal between the Seine and Saone. It occurred 

 to M. Galliot, an engineer at Dijon, to utilise the water power 

 of the fall of water at the lock sluices to drive turbines and 

 dynamos, the current obtained being used to propel the boats 

 on the canal. The electric power is conveyed along the canal 

 by means of a wire supported on posts, and each tow-boat is 

 provided with a motor which takes its current from this wire. 

 The propulson of the tow-boat is effected, not by means of a 

 screw propeller on the boat, but by a train of gear wheels 

 connecting the motor to a chain which extends along the bottom 

 of the canal, and by means of which the boat drags itself along. 

 In addition to working the canal boats, the electric power is 

 utilised to light up the interior of a tunnel through which the 

 canal passes. 



A PROPOSAL for a standard of " noraaal air " is made by M. A. 

 Leduc in the Comples Kendiis. It is to be one litre of air taken 

 at a place outside any town in a level country, and during calm 

 weather. Freed from carbonic acid and water vapour, as well 

 as traces of other accidental gases, such a litre of air would 

 contain 23"2 per cent, by weight of oxygen. Since this propor- 

 tion is variable in the same place by about 4 units in the second 

 decimal place, it is useless to determine the weight of this litre 

 of air to within more than i/ioooo of its value. A careful series 

 of determinations gave i'2932 gr. for this weight at o^^ C, at 

 the latitude of Pari;, and at 760 mm. pressure. Under 

 I C.G.S. atmosphere, this weight would be i "2758 gr. This 

 Stan lard would be sufficiently well defined for most practical 

 purposes, but where greater accuracy is required, M. Leduc 

 proposes to employ nitrogen as a standard of reference for gas 

 densities. The weight of the normal litre of nitrogen at Paris 

 is i'2570gr., or i'24 gr. under i C.G.S. atmosphere, within 

 O'l mgr. 



The Journal de Physique for December contains a paper by 

 M. Violle, on the electric furnace and the light given out by, 

 and the temperature of, the electric arc. In a lormer note a 

 description of the form of furnace used by M. Violle has been 

 given. The author considers that his experiments show that 

 the electric arc is the seat of a perfectly definite physical pheno- 

 menon, namely, the ebullition of carbon, for the arc is character- 

 ised by a constant brightness {i.e. the light given out by a giv.'n 



