232 Intelligence and Miscellaneous Articles. 



could hold about three pounds at each pole, and that the material 

 investigated was moved easily on the surface of mercury. He 

 also observed that the various kinds of asbestos are not magnetic 

 to the same extent. He distinguishes "ripe" asbestos, consisting 

 of short fibres in the same direction and of a straw colour ; this is 

 strongly magnetic and hangs to the poles. Another kind which 

 he describes as " unripe," of greater tenacity and prismatic shape, is 

 feebly magnetic. 



I used a steel magnet which could support 3 kilos at both poles 

 together, and found that a variety of asbestos of greenish colour 

 and firm texture was only very slightly attracted when it was 

 brought in a movable position opposite the poles of the magnet. 

 On the other hand, asbestos cloth woven without any filling, of a 

 grey kind, was attracted to both poles and held there like a thin 

 iron wire. This was still more remarkably seen in a thin strip of 

 what is known as asbestos-paper, about 4 centim. long and 0*3 

 centim. in breadth. This jumped from a distance of 1 centim. 

 towards the poles of an electromagnet with a lifting force of 5 kilo. 

 This strip snowed afterwards (as Brugmans had already proved) 

 slight polarity ; I noticed at least that the pole of a magnetic 

 needle was afterwards unequally attracted by the ends of the strip. 

 With an electromagnet of about 100 kilos lifting-power the strip 

 could also distinctly attract fine iron powder at the end turned 

 away from the pole. 



A square piece of asbestos paper, 15 ceutim. in the side, moved 

 from a small distance towards the poles, and remained there 

 even against a slight counterpoise. Of course small fibres of 

 asbestos and splinters acted like fine iron turnings, and even from 

 a distance of 8 centim. came in contact with the poles. Most 

 preparations of asbestos for technical purposes are made with a 

 packing the composition of which I do not know. I think, however, 

 that even if iron should be among the constituents it would be in 

 chemical combination with other elements as it is in the mineral 

 itself, and, accordingly, could not be considered as the cause of the 

 remarkably strong magnetism ; there are evidently several iron com- 

 pounds which show no attraction, and, as has been already observed, 

 a preparation without filling was also strongly magnetic*. 



In any case the observations of Swinton must not be disregarded 

 in practice, since the use of plates of asbestos may give rise to 

 sources of error in sensitive magnetic instruments. — Wiedemann's 

 Annalen, June 1895. 



* I boiled some grey asbestos, which showed itself strongly magnetic, 

 for a few hours with concentrated sulphuric acid; it had become quite 

 white and had retained the magnetic property. 



