1903.] 



Some Experiments in Magnetism. 



7 



For some time the writer regarded these results, and many others 

 of the same kind obtained from the same salt, as clear indications that 

 these crystals are orientated from their earliest growth, since very few 

 ever changed their position unless the crystals were crowded, and that 

 the molecule, or the crystal element, is magnetic, but he has failed 

 again and again to obtain any indication of orientation with the same 

 strongly magnetic salt, under what were, so far as could be judged, 

 similar circumstances, and lastly, by wiping the glass slide in a given 

 direction, he found it possible to produce a species of orientation in 

 other directions. The very fact that the orientation in these photo- 

 graphs is such that the length of the rectangles lies parallel to the 

 length of the microscope slide, which is presumably the direction in 

 which it is most often wiped or dusted, makes him the more unwilling 

 to accept the photographs as evidence of any magnetic effect, but he 

 feels it only wise to point out that the orientation produced by 

 scratches has never in his experience produced quite the effect seen in 

 this photograph, the grouping of the crystals has been different, 

 leaving no difficulty in tracing the line which gave rise to the orienta- 

 tion, whereas on these photographs this is scarcely possible ; the 

 distribution of the orientated crystals themselves is not linear. So 

 that, in the mind of the writer, in spite of the arguments adduced, and 

 the fact that no such clear case of orientation as that shown has been 

 observed with any other substance except the corresponding potassium 

 salt (although very many have been tried), it is still an open question 

 whether the orientation visible in fig. 1 is, or is not, due to magnetism. 



After these experiments made at ordinary temperatures, the writer 

 turned his attention to the formation of well-known magnetic bodies 

 in the magnetic field. Flowers of sulphur and levigated soft iron 

 particles were taken in the proportion in which they combine to form 

 the magnetic sulphide of iron Fe 3 S 4 , and were thoroughly mixed 

 together. The mixture was poured into a small paper tube, loosely 

 corked at the lower end, and this tube was placed vertically between 

 the poles of a powerful electro-magnet, arranged so that the tube 

 stood parallel to the lines of force between the poles, the last being 

 bored, and the little tube standing in the position of the heavy glass in 

 Faraday's celebrated experiment. The current was then switched on, 

 and, at the same time a flame was applied to the mixture where it 

 projected into the air at the top of the tube. As soon as the iron and 

 sulphur began to combine, the flame was withdrawn, and the wave of 

 combination descended right through the mixture. The current 

 through the magnet coils was maintained until the tube had had time 

 to cool ; the latter was then removed, the paper carefully taken off, dis- 

 closing a fairly tough rod of sulphide. This was found to be a magnet, 

 weak, but unmistakable, its poles being disposed as one would naturally 

 expect. Similar experiments were then made with mixtures of iron 



