C. GENERAL PHYSICS. 135 



electrical dissipation be due, as is commonly thought, to the 

 successive transfer of minute quantities of electricity from 

 the isolated body to the atoms of the surrounding gas, then 

 the laws followed by this phenomenon may be deduced from 

 the general principles established by Maxwell and Clausius 

 in their works on the constitution of gases, and that, accord- 

 ino- to these, we oug^ht to have the foUowino; general laws : 

 1. The coefficient of dissipation is inversely proportional to 

 the square root of the absolute temperature of the gas. 2. It 

 is proportional to the pressure of the gas. 3. It depends on 

 the nature of the gas. 4. The dissipation must follow Cou- 

 lomb's law, which is based upon observation, and requires 

 that the logarithm of the quantity of the electric charge must 

 diminish proportionally to the time. This last theoretical 

 result, supported as it is by the observations of Coulomb and 

 others, needs no further consideration ; but, in support of the 

 iirst three deductions, the author submits a number of spe- 

 cial experiments and observations made by himself on air 

 and hydrogen. The apparatus employed by him consisted 

 essentially of a bell-glass filled with gas at any desired ten- 

 sion, and within which were two light gilded balls one fixed, 

 the other movable. The latter was suspended from one end 

 of a light horizontal bar, to which was fastened a magnetic 

 needle, and all of which hung by a single fibre of silk. The 

 gilded balls, being equally charged, repelled each other to 

 such a distance that the repulsive force was balanced by the 

 mao-netic movement of the needle. The latter afibrded the 

 convenient means of determining at any time the extent to 

 Avhich the balls had lost their electric charges. Rejecting 

 all the observations in which a small error in observation 

 could entail an appreciable effect upon the resulting coeffi- 

 cient of dissipation, and confining himself to the most accu- 

 rate results, Boboulieff finds (1) that the dissipation in air 

 diminishes with the diminution of pressure, and (2) that the 

 dissipation in hydrogen is less than in the air at the same 

 pressure. In some of these experiments the charge of the 

 two gilded balls was maintained for eight or ten days, dur- 

 ing which interval observations were regularly made upon 

 them. Journal of the Physical and Chemical Society^ 1873, 

 36. 



