History, pede ftir I' Electricite, Par. 1781. Milner's Experiments 

 ,-- ' and Observations on Electricity. Kuhn Geschiclite der 

 Electricitat. Leipz. 1783. Tressan sur le Fluide Elec- 

 trique, Par. 1786. Bennet's New Experiments, Derby, 

 1789. Brooke on Electricity, 1790- Peart on Eleciri- 

 cily and Magnetism, Gainsborough, 1791- Peart on 

 Elt-clric Atmospheres, 1793. Adams on Electricity. 

 Lampadius uber Electricitat md ncirme, Berl. 1793. 

 Cavallo's Electricity, 3 vols. Lond. 1795. Morgan's 

 Lectures on Electricity, 2 vols. Kratzenstein Theoria 



ELECTRICITY, 429 



Electricitatis, Hoi. 174<6. J. Euler de causa Electrici- 

 tails, Petersb. 1755. Dutour sur la matiere electrique, 

 Par. 1760. Laurentii Beraud Theoria Eleclricitatit, 



I'etersb. Heidmann Tkeorie de I' Electricite, 2 vols. 

 Vienna, 1799- Carpue, Introduction to Electricity and 

 Galvanism. Cuthbertson's Practical Electricity, Lond. 

 1807. Eyewater's Essay on the Hiitory, Practice, 

 and Theory of Electricity, Lond. 1810; and Singer's 

 Elements of Electricity and Electro-chemistry, Lond. 

 1814. 



History, 



PART I. DESCRIPTIVE ELECTRICITY. 



Oe*aii.'ive DESCRIPTIVE Electricity, is that branch of the science 

 I'lectricity. which describes all the various phenomena which are 

 "V' either produced, or supposed to be prqduced, by the 

 same cause as the phenomena of excited amber. It na- 

 turally divides itself into three heads : I. The pheno- 

 mena of electricity produced by friction; II. The phe- 

 nomena of electricity produced without friction ; and 

 III. The effects of electricity, comprehending its me- 

 chanical, chemical, and magnetical effects, and its influ- 

 ence upon animal and vegetable bodies. 



CHAP. I. 



On ihe Phenomena of Electricity produced by Friction. 



the phe- ^ s fr' ctlon ' s tne mean which has almost always been 

 of employed for the production of electrical phenomena, 

 icity and as the various discoveries which have been made 



luced by respecting the communication, the distribution, and the 

 dissipation of the electric matter, have been made by 

 electricity excited in this manner, we shall introduce 

 into the present Chapter an account of these important 

 results, although they are equally deducible when the 

 electricity has been either excited by heat, or obtained 

 from any other source. 



SECT. I. On the Production of Electricity by Friction. 



3n the pro- ^ F we ru ^ > a P' ece f amber with dry fur, or woollen 

 cloth, and then hold the amber over any light substances, 



lectricity such as small pieces of paper, or the down of a feather, 

 rj friction, the light body will be attracted by the amber. The 

 same effect will be produced, by rubbing the glass of a 

 watch against the sleeve of the coat; and still more 

 powerfully, by rubbing a glass tube with a piece of dry 

 silk. In this latter case, when the tube is rubbed in 

 the dark, sparks of brilliant light, accompanied with a 

 crackling sound, will be emitted as long as the friction 

 is continued. In like manner, if a dry black silk rib- 

 bon, about two feet long, be laid upon a white one of 

 the same length, and be drawn over woollen cloth, or 

 silk velvet, or even between the finger and the thumb, 

 they will be found to adhere strongly to each other. 

 When separated, they will attract one another, and rush 

 together with considerable velocity. In a dark room, 

 the separation of the ribbons will be accompanied with 

 a flash of light ; and any one of the ribbons, when sepa- 

 rated from the other, will attract light substances like 

 the amber and the glass already mentioned. 



Now in these three simple experiments, the amber, 

 the glass, and the silk ribbons have obviously received 

 new properties, wlu'ch they did not possess before they 



were rubbed, viz. the property of attracting light bodies, Descriptive 

 and the property of emitting light in the dark. These Electricity. 

 properties are called electrical. The amber, the glass, s ""T""" > ' r 

 and the ribbons, are said to be excited by friction. The 

 power of drawing to themselves light bodies, is called 

 electrical attraction, to distinguish it from the attractions 

 of cohesion, of gravity, and of magnetism. The light 

 emitted in the dark, is named the electric spark, or elec- 

 tric light ; and the body which is capable of acquiring 

 these properties, is called an electric. 



By rubbing a great number of other bodies with 

 woollen cloth, fur, silk, &c. they are found to exhibit 

 the same properties as amber and glass ; while another 

 class of bodies exhibit no such properties, with what- 

 ever substances, and in whatever manner, they are rub- 

 bed. Hence bodies are divided into two great classes, 

 viz. electrics, or those which acquire by friction the fa- 

 culty of exhibiting electrical properties ; and non-elec- 

 trics, or those which are incapable of acquiring electri- 

 cal properties by friction. The following is a list of 

 electrics arranged in the order of their perfection, those 

 being regarded as the most perfect which produce the 

 most powerful electricity by the least friction. 



Talk of Electrics. 



Glass, and all vitrifications, even those of metallic sub- Table 01 

 stances. electri .. 



The precious stones, such as diamonds, garnets, rubies, 

 topazes, emeralds, sapphires, the most transparent of 

 which are generally the most perfect. 



Amber. 



Sulphur. 



Shell lac, and all resinous bodies, and resinous com- 

 pounds. 



Bituminous substances. 



Silk. 



Wax. 



Cotton. 



Dry animal substances, as feathers, wool, hair. 



Dry paper, parchment, and leather. 



White sugar. 



Sugar candy. 



The vapour of quicksilver. 



Perfect Torict'/lian vacuum. 



Ice of distilled water, at the temperature of 13" o4' 

 Fahrenheit. 



Oils. 



Metallic oxides. 



Ahes of animal and vegetable substances. 



Dry vegetable substances. 



Hard stones, the hardest of which are the best electri*.-. 



