1824.] On Motions produced in Fluid Conductors, tyc. 271 



which the workmen call brambles (ronce), and which are seen 

 on the beautiful Indian blades, are the consequence of the way 

 in which they are forged. If steel be drawn out lengthwise, the 

 veins will be longitudinal ; if it be equally extended in all direc- 

 tions, the damask will have a crystalline appearance; if it be 

 rendered wavy in both directions, it will be shaded like the 

 eastern damask. But few trials are necessary to produce any 

 sort of watering that may be desired. 



" The best process for developing the damask, so that the 

 steel may become black or bluish without losing its polish, is, 

 in my opinion, that which is employed in the East. It is 

 described, by M. le Vicompte Hericart de Thury, in a report 

 inserted in the ' Bulletin de la Societe d'Encouragement,' 

 No. 220, for December, 1821, twentieth year, p. 361." 



Article XI. 



The Bakeriau Lecture. — On ceitain Motions produced in Fluid 

 Conductors when transmitting the Electric Current. By 

 J. F. W. Herschel, Esq. FRS. 



(Concluded from p. 176.) 



17. In many liquids, and especially in solutions of the nitrates, 

 there is formed not only a current radiating from the negative 

 pole, but also one from the positive, which even has in some 

 cases a preponderance over the other. These co-exist in the 

 mercury ; and, in consequence of their action, a zone of equili- 

 brium is formed in the globule, nearer to one or the other pole, 

 as the antagonist current, is more or less violent. The best way 

 to render the influence of this counter-current sensible is to 

 operate on a large quantity of mercury, under dilute solutions, 

 keeping the negative pole at a distance, and the positive very 

 near, in this way there are few liquids which, when the pile is 

 in good action, do not show some signs of a counter-current 

 from the positive pole. The cause of this will be evident, when 

 we come to speak of the action of metallic alloys. 



18. If either pole be brought in contact with the mercury, no 

 currents are observed from the point of contact (at least when 

 the mercury is fresh and tho contact perfect) but strong ones 

 are always produced, radiating from the other. If it be the 

 negative pole which is made to touch, it amalgamates with the 

 mercury, which remains bright, and the currents radiating from 

 the positive are visible to the eye, and generally very powerful. 

 On the other hand, if the positive pole be in contact, the oxida- 

 tion of the metallic surface is usually so rapid as to prevent the 

 currents becoming visible, but a momentary start of the surface 



