Intelligence and Miscellaneous Articles. 



255 



ON THE INFLUENCE OF THE TEXTURE OF IRON UPON ITS MAG- 

 NETISM. BY L. KULP, OF DARMSTADT. 



The following is a statement of two series of experiments which 



I made upon two iron bars of unlike texture, 48 millims. in length, 



II millims. in thickness, and each weighing 34-2 grammes. 



Bar I. had a granular, while bar II. had a decidedly fibrous struc- 

 ture — recognized in both bars from the fracture-surfaces. For the 

 observations the bars were placed in an induction-coil of 1600 

 turns ; and the moments were read off in the well-known manner 

 on a Wiedemann mirror-compass distant 500 centims., by means' 

 of a telescope with scale at 4 metres distance. 



In the following Tables the first columns contain the relative 

 intensities of the current through the coil, and the second contain 

 the deflections (in scale- divisions) corresponding to the respective 

 moments. 



Table a. — Bar I. 



Table b. — Bar II. 



Relative intensity 

 of current. 



Deflection. 



0-0874 



3-5 



0-1727 



8-5 



0-2962 



16 



0-4142 



23-5 



0-5984 



34 



0-7399 



43 



0-9260 



56 



10761 



65 



1-6642 



103 



Relative intensity 

 of current. 



Deflection. 



00722 

 0-1907 

 0-3482 

 0-5317 

 0-7080 

 0-9067 

 1-0913 

 1-6642 



4 

 10 

 19 

 29 

 41-5 

 55 

 65 

 104 



From this we get the remarkable result that, for equal intensities 

 of the current, the two bars gave almost exactly the same induced 

 magnetic moments, and consequently that the very different struc- 

 ture of the two pieces of iron employed had no influence whatever 

 upon the amount of the induced magnetic moment. — Poggendorff's 

 Annalen, 1875, vol. civ. pp. 320, 321. 



ON MAGNETS FORMED FROM COMPRESSED POWDERS. 

 BY J. JAMIN. 



In 1836, in the Memoires de VAcademie of Stanislas, De Haldat 

 published an interesting observation : he had put iron filings into 

 a brass tube closed by two screw stoppers ; he magnetized it by the 

 usual process, and ascertained that it had acquired, and retained, at 

 its extremities two opposite poles. The polarity was not sensibly 

 augmented when the stoppers were tightened, and diminished but 

 slowly when increasing quantities of river-sand were mixed with 

 the filings. In all cases the polarity remained very feeble ; and it va- 

 nished when the metallic grains were displaced by agitating the tube. 



