536 : DR. SCHULTHESS ON THE APPLICATION OF 
tricity to make soft iron magnetic. In the year 1825, Sturgeon mag- 
netized cylindrical horseshoes of soft iron by means of copper wires 
wound round them, connecting the ends of the wires with the plates of 
an electromotor. Professor Van Moll of Utrecht saw this experiment 
performed in the physical laboratory of the London University by Mr. 
Watkins, and he obtained on repetition those remarkable results de- 
scribed in Bibl. Univ., cab. 45. p.19. This new method of communi- 
cating such great attractive power to iron created in me the desire of 
repeating the experiments, and principally of taking into consideration 
the application of this attractive power, which it appears may be 
infinitely increased, to some useful purpose. I give these experiments 
to the public in the conviction that a force so easily evolved and so very 
powerful justifies repeated and varied experiments. In my experiments 
the electromotors employed were without doubt smaller than any hi- 
therto used, and these notwithstanding produced the same results: new 
circumstances and new laws were observed and discovered respecting 
the manner of increasing the magnetic power evolved by electromotors, 
of producing.in them currents now similar, and now different, some- 
times in the same, sometimes in opposite directions, and by the success 
of these experiments of setting a lever in motion in different ways, and 
thus finally enriching natural philosophy with a new motive power.” 
It is easy to imagine with what avidity I read this notice, partly from 
joy at seeing my idea, of the practical application of which I still had 
many doubts, mentioned by another person, and partly somewhat vexed 
that the priority of my invention, if it really was as useful as my fancy 
made me think it, was snatched away from me. I therefore read with 
intense eagerness this paper; but my expectations were in a great mea- 
sure disappointed ; for it was only at the end that Dal Negro gave some 
short, and to me not altogether comprehensible hints concerning his ex- 
periments on the application of the power of electro-magnets to moving 
machinery, after having described a considerable number of other expe- 
riments, the principal object of which was to give with the least possible 
means to a soft-iron horseshoe the greatest possible magnetic power. He 
took seven different horseshoes, varying from 0°29 to 5 killogrammes* 
in weight: the copper wire with which he enveloped them, in from 37 
to 64 coils, had a diameter of 8°2 to 8*4 mill. ; the zine plates of the four 
different electromotors had surfaces = 3, 3, 24, and 42 square feet 
each ; the dilute acid employed consisted of ;4, of sulphuric acid and 75 
of nitric acid in 1 of water. With these electro-magnets Dal Negro 
obtained remarkably powerful results. The largest, (weighing 5 kil- 
log., surrounded with 64 coils of copper wire of 8-4 millim. diameter, ) 
with the armature weighing 2 killog., when connected with the largest 
electromotor, supported from 108 up to 117 killog. Dal Negro attri- 
* [1 millimetre = ‘03937 English inch. 
1 killogramme = 2 lbs. 5 oz. 5 dram.—Trans. | 
