When was it proposed that electricity and magnetism were distinct effects by scientists William Gilbert ?
In his work " Tentamen Theoria Electricitatis et Magnetism " , published in Saint Petersburg in 1759 , he gives the following amplification of Franklin 's theory , which in some of its features is measurably in accord with present - day views : " The particles of the electric fluid repel each other , attract and are attracted by the particles of all bodies with a force that decreases in proportion as the distance increases ; the electric fluid exists in the pores of bodies ; it moves unobstructedly through non-electric ( conductors ) , but moves with difficulty in insulators ; the manifestations of electricity are due to the unequal distribution of the fluid in a body , or to the approach of bodies unequally charged with the fluid . "