58 



ELECTRICITY. 



tion of one or two additional brass springs, 'experiments, it may be laid down as a 



pressing; on the main spring. 



Another 2;old leaf electroscope is con- 



fundanienlal truth, in terrestrial physics, 

 that friction has no other influence in elet 



nected with the brass piece, into which trie phenomena, than that of disturbing 

 the rubbers are fixed. Many trials were the equilibrium of the eleetrie fluid in 

 made before tlie machine was brought to a 'such a manner, that one body, by acquir- 



sufficiently small power. The following 

 are the dimensions when it nearly succeed- 

 ed, though still too strong ; the spindle is 

 a solid glass cylinder ver}' little more than 

 one fourth of .an inch in diameter, and 

 covered with sealing-wax at both ends, 

 for the purpose of insulating about three 

 fourths of an inch in length in the middle 

 where the friction is produced. The rub- 

 ber is simply a brass spring, bent at one 

 end to fit the upper part of the cylinder. 

 Small as this machine is, it was found 

 necessary to move it very slowly, to pre- 

 vent too great a motion of the electro- 

 scopes. 



Mr. De Luc next states his experi- 

 ments with considerable precision and 

 minuteness. In the first the cylinder was 

 glass, and the rubber brass ; and it ap- 



ing a certain portion of it above what it 

 had before, is rendered /?0527n'e, and that 

 the other is found negative^ as having lost 

 that quantity. 



It is only when its equilibrium is dis- 

 turbed that it is manifested to us. The 

 electroscope is our first test of this distur- 

 bance; but if the bodies, either conduc- 

 tors themselves, or associated with C07i- 

 ductors, are of sufficient size, and the 

 electric fltaid between them has arrived to 

 a certain degree, it is manifested by a 

 spark darting from one to the other, and 

 the equilibrium is restored." 



Observations. We cannot altogether 

 adopt the whole of Mr. De Luc's ingeni- 

 ous theories, which appear to us to want 

 the great merit of simplicity: his experi- 

 ments are interesting, and so far as they 



peared that the former received electric are directed to the establishment of a 

 fluid from the latter by means of the fric- basis for the explanation of elementary 

 tion, and communicated it through the facts, they must be considered as highly 



prime conductor to one of the electro- 

 scopes, which diverged positively, while 

 the other diverged negatively. In the 

 second experiment the communication be- 

 tween the rubber and the prime conductor, 

 was restored by means of a wire, and the 

 motion of both electroscopes immediately 

 ceased. In the third experiment, both 

 the rubber and the cylinder were glass, and 

 the latter obtained electric fluid from the 

 former. 



Experiment fourth was made with glass 

 and sealing-wax ; 5th, with glass and In- 

 dian-rubber; 6th, with brass and sealing- 

 wax; 7th, with Indian-rubber and sealing- 

 wax; and the Sth, with some of the beads, 

 of the size and color of a cherry, worn by 

 Indian women, mounted instead of a 

 cylinder, and acted upon successively by 

 rubbers of brass and sealing-wax. From 

 all these experiments the author draws the 

 following conclusions, 



" Such are the constant phenomena ob- 

 served at the fountain head of all the elective 

 effects which it is in our power to produce, 

 and they depend on friction, respecting 

 which various systems have been fabricat- 

 ed. Now from the whole tenor of these 



important; but we do not think that his 

 hypothesis are such as materially facilitate 

 the connection of these facts with each 

 other, which in the investigation of so 

 abstruse a subject, is all that we have at 

 present a right to expect from any hypo- 

 thesis; for a theory, which shall in all 

 cases correctly represented the intimate 

 nature of the operations concerned, is 

 scarcely to be expected from the utmost 

 exertions of human intellect continued 

 and combined for many ages. 



Retrospect. 



DEFINITION OF TERMS. 



Beginning at the letter B. 

 Barytes in Mineralogy and Chemistry, 

 an earth, discovered by Siieele in 1774 

 and may be obtained from ponderous spar, 

 or sulphate of barytes, as it is now called, 

 by the following process, for which we 

 are indebted to Vauquelin. Reduce the 

 mineral to a fine powder, mix it with the 

 eighth part of its weight of charcoal pow- 

 der; and keep it for some hours red hot in 

 a crucible, and it will be converted into 

 sulphuret of Barytes. Dissolve the sul- 

 phuret in water, and pour nitric acid into 



