Electricity.

Date:
[1829]
Catalogue details

Licence: Public Domain Mark

Credit: Electricity. Source: Wellcome Collection.

    4/150 (page 14)
    tricity can be obtained at pleasure, both from glass and sealing-wax, by varying the nature of the substance with which they are rubbed. Hence the vitreous electricity of Du Fay is now called positive electricity; and the resinous, negative electricity; terms first proposed by Dr. Franklin. 13. To the labors of Messrs. Grey and Wheeler, and their coadjutors Du Fay and Nollet, all subsequent electricians are highly in¬ debted; their means of research were extended by the improvement of electrical apparatus, ne¬ cessarily resulting from the discovery of conduct¬ ing and non-conducting power; whilst the generalisation of electric phenomena by Du Fay, and his discovery of the distinction between positive and negative electricity, was an enlarge¬ ment of the existing sphere of knowledge in a degree before unparalleled. From this period, indeed, the science assumed a more important aspect, its cultivators increased in number, and the communication of their researches consti¬ tuted a prominent feature in the transactions of the most celebrated societies and academies of Europe. 14. It was in the year 1745 that the remarkable properties of the Leyden phial were first ob¬ served. This discovery was merely accidental; yet it tended, more than any other discovery hi¬ therto made, to promote the progress of electri¬ city. The circumstances that led to this discovery were the following:—Professor Muschenbroeck observed, that when conducting bodies were placed on glass, &c., and electrified, their elec¬ tricity was very soon carried, off by the conduct¬ ing particles floating in the atmosphere; he therefore imagined, if a conducting substance were put into a glass phial, that it could be charged much higher than in open air, as the glass would protect it from the dissipating action of the atmosphere. 15. This idea he attempted to put in practice by filling a small phial with water, which is a conducting substance. For this purpose he passed the end of a wire through the cork of the phial, so as to touch the water, and then charged the water by bringing the wire in contact with the prime conductor, but found no extraordinary result from the experiment. Mr. Cuneus, of Leyden, who was one of the party when the pro¬ fessor made the experiment, repeated it after¬ wards; and, happening to hold the phial in his hand, after he had connected the wire with the prime conductor, until the water, as he supposed, had received a full charge of electricity, and then applying his other hand to unloose the wire from the conductor, he received such a sudden shock in his arms and breast, as filled him with asto¬ nishment. 16. The report of such a strong effect of the electric power immediately raised the attention of all the philosophers in Europe. Many of them greatly exaggerated their accounts ; either from a natural timidity, or a love of the marvel¬ lous. M. Muschenbroeck, who tried the experi¬ ment with a very thin glass bowl, told M. Reau¬ mur in a letter written soon after the experiment, that he felt himself struck in his arms, shoulder, and breast, so that he lost his breath; and was two days before he recovered from the effects of the blow, and the terror. He added, that he would not take a second shock for the whole kingdom of France. Mr. Allamaud, who made the expe¬ riment with a common beer glass, said, that he lost his breath for some moments; and then felt such an intense pain all along his right arm, that he was apprehensive of bad consequences, but it soon after went off without any inconvenience, &c. Other philosophers, on the contrary, showed their magnanimity, by receiving a num¬ ber of electric shocks as strong as they could possi¬ bly make them. Mr. Boze wished that he might die by the electric shock, in order to furnish, by his death, an article for the memoirs of the Aca¬ demy of Sciences at Paris. But, adds Dr. Priest¬ ley, in his history of electricity, it is not given to every electrician to die in so glorious a manner, as the justly envied Richman. Public curiosity was promptly and highly excited by this disco¬ very, and all Europe was presently filled with itinerant exhibitors of the Leyden Jar, who ob¬ tained a livelihood by administering the electri¬ cal shock. The experiment was repeated and varied by the electricians of every country, and an explanation of the principle on which the effect depends, was offered by Dr. Franklin of Ame¬ rica, and Dr. Watson in England, at the same time, without the one knowing that the other was engaged in the pursuit. The propositions of these two philosophers, observes Mr. Singer, were nearly similar; but that of Dr. Franklin being the more perfect, and having a real priority of publication, was adopted, and has been since celebrated as the Franklinean Theory of Elec¬ tricity. He referred all electrical effects to the motion of a peculiar fluid, repulsive of its own particles, and having an attraction for all other matter. And he considered the opposite elec¬ tricities of glass and sealing-wax as indications of different states of this fluid : the vitreous elec¬ tricity being the plus or positive state, and the resinous the minus or negative state. All bodies can contain a certain quantity of electric fluid in a latent state. If this quantity be increased they become electrified positively ; if it be diminished they are rendered negative. The production of electrical effects is therefore nothing but the result .of the unequal distribution, by art, of a naturally diffused fluid. Such are the leading principles of the Franklinean theory ; they have been con¬ sidered mathematically by Mr. Cavendish, by JEpinus, and others, and, with some modifications, apply to most of the electrical phenomena at present known. 17. Frequent experiments, attended with close observation, wrere likely enough to lead to im¬ portant results in this interesting science; and we have now arrived at a period in its history which is perhaps the most distinguished of any. We allude to the discovery of the identity of elec¬ tricity and lightning. Mr. Grey and Dr. Wall seem to have been the first who thought of the resemblance between thunder and the snapping noise which is heard when an excited electric is approached by a conducting substance. The abbe Nollet, Mr. Winckler, and others, also enumerated many resemblances between the phenomena of electricity and those of thunder;