The medical application of electro-magnetism / by Samuel B. Smith.
- Smith, Samuel B., approximately 1794-
- Date:
- 1853 [©1850]
Licence: Public Domain Mark
Credit: The medical application of electro-magnetism / by Samuel B. Smith. Source: Wellcome Collection.
Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.
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![Electroscope.— By the aid of an Electroscope we are enabled to ascertain the different electric states of substances with great precision. For instance, we can detect the different electrical states of the inside and outside of various articles of clothing. A person's coat, when pulU ed oft'after a smart walk, is always highly electrical; having the inside and outside in different states.—Sturgeon s Galv. p. 81. The Vital Electric Action on Different Animals.— In the hum in Bio-Voltaic battery the completion of the circuit is through certain Dynamic nerves, which passing through to the flesh, produces Motion—to the electric batteries of certain fishes, produces Elec- tricity—to the light-generating apparatus of animals, ] reduces Light. Besides these forces, more or less heat is produced in most creatures. —Smce, p. 49. DiFrERENT Polarities in the same Metal.— Even one and the self-same mass of an individual metal, is electro-polar on its oppositi^, surfaces, when not of the same degree of polish or tex- ture.—Sturgeon s Galv. p. 70. Place a zinc plate on a sheet of glass, and a copper plate on the zinc. In this place the copper is negative and the zinc positive.— Ibtd. p. 70. An Experiment showing the Polarity of a Dry Pile.— Let the Pile be placed on two gold-leaf electroscopes, having one pole on each—both pairs of gold-leaf divei-ge, and to about the same extent. We now remove the pile by taking hold of the middle of the glass tube. The diverging continues, and by testing with exci- ted sealing-wax, or by glass, we find one of the electroscopes to be electro-positive, and the other electro-negative.—Ibid, p. 75. The Electric Current from the Feet to the Head.— It is remarkable, (says Golding Bird,) that in the batrachians generally, especially in the frog, proper electrical currents are detected cnpable of deviating the needle of the galvanometer to 5°. Its direction is always definite, from the feet to the head. Tliis curious and remark- able fact was, I believe, first pointed out by Nobili, but accurately studied by Matteucci, to whose researches I have so often referred.— £ii-d in Lond. Med. Gaz. April, 1847, The Preferability of Electro-magnetism to Galvanism.— There are, (says Golding Bird,) many serious inconveniences attending the use of Galvanic electricity, and not the least of these is the bulky and unmanageable form of apparatus required for its excitation in a state of even moderate tension. On this account, this form of electricity is now seldom employed, and in my own practice I confess I never use it ; for the electricity of dynamic induction is so much easier excited, and, being the same in essence, has always been, so far as my ov/n expe- rience has extended, substituted for it,—Lond. Med. Gaz. June, 1847. Muscular Contraction ensues from the material existing in the ultimate fibre being increassed in bulk by changes taking place in consequence of the Voltaic circuit.—Smee, p. 51. 4#](https://iiif.wellcomecollection.org/image/b21078373_0050.jp2/full/800%2C/0/default.jpg)
