38. PILTCHIKOFF’S EXPERIMENT. LIQUID BAS-RELIEF FACSIMILES BY ELECTRIC DISCHARGE. _Pro. Acad. Sci._, Paris, March, ’94. _The Electr._, Lon., April 13, ’94, p. 656.—These shadow pictures were obtainable either with the anode or cathode, the particular machine employed being a large Voss. To either pole was electrically connected a pointed wire which was held just above the surface of castor oil, in a copper pan. A remarkable effect was obtained of the shadow of a piece of mica, Fig. XI, of whatever shape, located between the point and the surface. § 24. Let it be observed that this shadow was not one in the sense of light and darkness but it consisted of a plateau within a depression, the former being of the same shape as though it were a shadow of the mica triangle. To illustrate the experiment better, let the mica be supposed to be removed, then will there be a depression formed in the oil upon bringing the metallic point near to the surface. Now insert the insulating sheet between the point and the surface, then will there be an elevation within the depression of the same shape that the shadow would be. 39. GERNEZ’S EXPERIMENT. DISTILLATION OF LIQUIDS BY DISCHARGE. _Phys. So._, Paris, 1879. _Nature_, Nov. 20, 1879, p. 72.—In order that the apparatus with which he experimented may be understood, imagine a tube standing vertically in another tube. The two concentric tubes communicate with each other at the top only. The Holtz machine is the generator. The liquids in the two tubes at the beginning stand at the same level. Sparks are passed through the adjacent air, which is in contact with both liquids. The liquid at the cathode rises and at the anode falls. § 38. Such was the experiment performed by Gernez. He was inclined to conclude that the effect was due to “An electrical transport of liquids along the moistened surfaces of the tubes.” When the liquid was alcohol, it actually went over as by distillation, three times as fast as water. A soluble salt in water increased the rate of distillation; and so also did the addition of a small quantity of sulphuric acid or ammonia. No distillation of bi-sulphide of carbon, tetra chloride of carbon, nor turpentine occurred. Query: Can alcohol be concentrated or practically distilled upon this principle? 40. DE LA RUE AND MÜLLER’S EXPERIMENT. STRIAE. BLACK PRINTS ON WALLS OF TUBE. _Phil. Trans._, 59, ’78.—Particles of the metal of the electrodes were deposited upon the inside of the glass forming permanent black striae or bands § 44, at points corresponding to the spaces between the luminous striae. § 6. near the end. ------------------------------------------------------------------------ CHAPTER IV -------