528 Intelligence and Miscellaneous Articles. 



such lines would be cut parallel to and touching each other, the 

 feeler of course passing in a corresponding manner over the drawing. 

 If, then, a means could be devised for causing the graver to act only 

 when the point of the feeler passed over a portion of the drawing, it 

 is clear we should get a plate engraved, line for line, with the object 

 to be copied. This is accomplished by placing the graver under the 

 control of two electro-magnets, acting alternately, the one to draw 

 the graver from the plate, the other to press it down on it. The 

 coil enveloping one of these magnets is in connexion with the feeler, 

 which is made of metal. The drawing is made on a metallic or 

 conducting surface, with a rosined ink or some other non-conduct- 

 ing substance. An electric current is then established, so that when 

 the feeler rests on the metallic surface, it passes through the coils of 

 the magnet, and causes it to lift the graver from the plate to be en- 

 graved. As soon as the feeler reaches the drawing, and passes over 

 the non-conducting ink, the current of electricity is broken, and the 

 magnet ceases to act, and by a self-acting mechanical arrangement 

 the current is at the same time diverted through the coils of the 

 second magnet, which then acts powerfully and presses the graver 

 down. This operation being repeated until the feeler has passed in 

 parallel lines over the whole of the drawing, a plate is obtained en- 

 graved to a uniform depth, with a fac-simile of the drawing. From 

 this a type-metal cast is taken, which, being a reverse in'all respects 

 of the engraved plate, is at once fitted for use as a block for surface 

 printing. — Journal of the Society of Arts; and Athenceum, June 17, 

 1854. 



ON THE FORCE WHICH GOVERNS CHEMICAL ACTIONS. 

 BY M. WITTWER. 



My object is to show that the force which governs chemical actions 

 is completelj'^ analogous to those which rule the actions of light, heat, 

 electricity and magnetism. 



Physicists determine the force of an electric current by the mag- 

 netic energy excited or by the deviation of the magnetic needle. 

 This deviation and Melloni's pile afterwards furnished them with the 

 means of measuring radiating heat. In my turn, I think it possible, 

 by the assistance of light and heat, to obtain the means of measu- 

 ring chemical force, whether we liave disengagement of light and heat 

 in a combination, or an absorption of these matters in consequence of 

 the separation of the chemical components. Bodies are either in a 

 state of stable equilibrium, when their separation requires a con- 

 tinued application of light, &c., as for instance, chlorine gas ab- 

 sorbed by water ; or in a state of unstable equilibrium, when they 

 only require the instantaneous application of these agents to modify 

 their condition (as for example, the explosive compounds) ; chemical 

 reactions may therefore be expressed as functions of light, heat, &c. 

 To arrive at the law which rules affinity when an atom of A com- 

 bines with several atoms of B, I admit the three following laws : — 



1. Two heterogeneous bodies exercise upon each other a chemical 

 action which decreases as the inverse square of the distance. 



