162 TEAK-BOOK OF FACTS. 



When pure water flows through a porous body, an electrical cur- 

 rent is elicited — a fact established by experiments, says M. G. 

 Quincke, may be stated concisely in these terms : — 



Some thirty layers of thin silk stuff were placed over each other 

 and attached over one tube of the apparatus ; another tube was then 

 adapted against the former, and the part separating them covered 

 thickly with sealing-wax. Owing to the wide pores of the silk, con- 

 siderably more water flowed through under equal pressure than when 

 the clay plate was employed. The linen was used in the same 

 manner. 



The other substances were applied in the form of powder, in a 

 glass tube of the diameter of the above tubes. The ends of these 

 tubes, the length of which varied, according to the substance 

 employed, from 20 to 45 niillinis., were ground flat, and over 

 them were placed discs of the silk stuff spoken of, to prevent the 

 flow of the fluid carrying away particles of the substance under exa- 

 mination. In the case of Bunaen's coal, the tube was closed with 

 plates thereof. 



Platina was made use of in the spongy form, iron as filings. The 

 glass had been reduced to powder on an anvil. Ivory and the 

 various kinds of wood were employed in the form of sawdust. It 

 was endeavoured in vain to press water through a porous plate of 

 wood, for the plate had to be luted in dry ; and on becoming moist, 

 even if cut perpendicular to the direction of the fibres, it warped so 

 much that it broke the sealing-wax or the tube. 



The direction of the electric current was not changed by adding 

 acids or solutions of salts to the distilled water, but it was con- 

 siderably weakened thereby. 



MOVEMENTS OF ELECTRIC FLDID. 

 The Rot. T. Rankin has read to the British Association a paper 

 " On the different Motions of Electric Fluid." The author, from 

 several very striking and vividly-described thunder-storms and their 

 permanent effects, concludes that sometimes the electric fluid moves 

 downward, sometimes upward, and sometimes horizontally. On 

 one occasion, sonic years since, about two o'clock, OB a night on 

 which it bad thundered almost incessantlv, a loud whizzing sound 

 was heard to pass over the rectory-house, which he i 1"' an 



aerolite ; a to e is the direction it had passed was 1 from 



the nature of the injury inflicted, the conclusion was drawn, that the 

 motion of cither tho aerolite or of the electric fluid had been nearly 

 horizontal. 



raoxBio tau. 

 An Electric Target has been brought into use by several Volun- 

 RAfls Companies, by means of which the necessity for ■ 

 marker or signal-man being stationed near so On For tho 



I iiit-] Hing by flags the portion struofc by the projectile) is 



Lher dispensed with, u conveying the informa- 



tion to the marksmen Ly means of ckctrie signals. 



