NATURAL PHILOSOPHY. Ill 



this question, and shows that " the velocity deduced along the wires, 

 in case the circuit is 607 miles long, is 28,524 miles per second." 

 He adds, "I place great confidence in these results, as every care 

 was taken to eliminate all possible sources of error." 



THE PROPAGATION OF ELECTRICITY IN GASEOUS BODIES. 



IN a paper read before the French Academy, at its sitting on April 

 16th, M. Matteucci, after noticing some of his former experiments, 

 says, " Since my first experiments, I have found that the law given 

 by Coulomb, for the loss of electricity in moist air, does not hold en- 

 tirely true for dry gases, and that in experimenting on these, the 

 results cannot be compared together, unless the experiments are made 

 at the same or nearly the same, temperature. It is known that Cou- 

 lomb found that the loss of electricity in the same conditions of the 

 atmosphere is proportionate to its intensity, so that the relation be- 

 tween them is constant. The dhTerence between my results and those 

 of Coulomb is, that the number which represents the relation between 

 the electric force lost in a minute and the mean force, is much smaller 

 than that given by Coulomb, and that it varies with the distance at 

 which the electric balls are kept ; and for each experiment made at a 

 given distance between them, the fraction which gives the relation 

 mentioned above increases as the electric charge diminishes. So that 

 in air, in hydrogen gas, or in carbonic acid, when dry, the loss of 

 electricity is not proportioned to its intensity, as Coulomb asserted." 

 He concludes by saying, " We must admit that the gaseous mole- 

 cules are attracted by the electrified bodies, and remain attached to 

 these bodies, attracting other gaseous molecules around them, so as to 

 propagate electricity as in solid bodies." 



THE CONDUCTING- POWER OF LTQUTDS WITH REFERENCE TO 



ELECTRICITY. 



THE conducting power of liquids varies with the temperature, but 

 in a proportion inverse to that in metallic wires, that is, it increases 

 with the rise of temperature. The fact has long been known, but 

 hitherto measurements were wanting. Edmund Becquerel concludes 

 from his experiments on this subject, which, however, are not very 

 numerous, that the increase of the conducting power proceeds propor- 

 tionally to that of the temperature. This assumption must, how- 

 ever, be regarded as a rude approximation to the truth. From a more 

 detailed, though still unfinished investigation of Hankel, we learn 

 that the conduction-resistance of liquids is very sensibly diminished by 

 warming, but that this diminution is not proportional to the change of 

 tempi- rat ure, but is greater for a given difference of temperature the 

 nearer this approaches to zero. The various liquids appear to corre- 

 spond tolerably in these variations, and only differ from one another in 

 this, that those solutions which contain a larger quantity of salts suffer 

 greater variation in their conducting power for the same differences of 

 temperature. It is singular, that the conductivity of a concentrated 



