MMiscellanies. 177 
2. Electro-magnetic experiments.—Professor Moun, under date 
of Utrecht, April 23, 1833, describes in the Bib. Univ. the result of 
various experiments to ascertain how far he could diminish the gal- 
vanic surfaces, and yet retain a considerable amount of magnetic pow- 
er. His horse shoe was cylindrical, and when straight, measured 
twenty four inches (English) in length ; diameter, two inches. It 
weighed with its spirals twenty nine pounds. ‘The iron was surround- 
ed with an envelope of silk, and around this were rolled two spirals 
(stnistrorsum) of soft iron of the diameter of ~; of an inch. These 
spirals were not covered either with silk or aa roller substance. The 
ends of these iron wires were soldered together, and communicated 
by other wires with the simple galvanometric apparatus, consisting 
always of a single element. The other extremities of these wires 
were also soldered to the zinc and copper plates of the voltaic ele- 
ment; for his experience, (he observes,) and that of many others, 
has taught him that a contact as intimate as possible between the spi- 
rals and the zinc and copper of the battery, can alone secure com- 
plete success. 
A little copper trough containing a plate of zinc of the surface (on 
one side) of seven eighths of a square inch, gave the horse shoe, 
(which had previously no sensible force,) a magnetic power which 
sustained twelve pounds. In a second experiment the tron sustained 
thirty nine pounds, and in a third forty eight pounds. Care was 
taken to prove that the horse shoe, prior to each experiment, had no 
sensible magnetic force. 
Prof. M. then took a piece of the smallest of the copper coin, and 
a piece of zinc of the same diameter, viz. about Z of an inch. The 
horse shoe, with this, supported 6? ounces. He then used two of 
these half cents, (as they are called in Holland,) united them by a 
copper wire, and placed between them a disc of zinc of the same 
diameter, and plunged the apparatus in a little wooden trough. ‘The 
horse shoe then supported 14? ounces. With a two cent piece of 
copper, (7 of an inch,) 2 lb. 5% oz. were sustained. With a twenty 
franc gold piece, it supported 13? ounces. With a silver piece of 
half a franc value, 2 inch in diameter, the weight sustained was 13 
Ibs. 32 oz. With a zinc plate of 43 inches square, between two 
plates of copper in a wooden trough, 80 Ibs. were supported. With 
a plate of zine of 104 inches square in a trough of copper, 224 lbs. 
The acid menstruum was very strong. 
Vou. XXVI.—No. 1. 23 
