In this work also he proved himself a great diplomat by remaining on terms of intimate friendship with Dr.Gray--a thing that few people were able to do.
Almost his first step was to overthrow the belief that certain bodies are "electrics" and others "non-electrics"-- that is, that some substances when rubbed show certain peculiarities in attracting pieces of paper and foil which others do not.

Dufay proved that all bodies possess this quality in a certain degree.
"I have found that all bodies (metallic, soft, or fluid ones excepted)," he says, "may be made electric by first heating them more or less and then rubbing them on any sort of cloth.

So that all kinds of stones, as well precious as common, all kinds of wood, and, in general, everything that I have made trial of, became electric by beating and rubbing, except such bodies as grow soft by beat, as the gums, which dissolve in water, glue, and such like substances.

'Tis also to be remarked that the hardest stones or marbles require more chafing or heating than others, and that the same rule obtains with regard to the woods; so that box, lignum vitae, and such others must be chafed almost to the degree of browning, whereas fir, lime-tree, and cork require but a moderate heat.
"Having read in one of Mr.Gray's letters that water may be made electrical by holding the excited glass tube near it (a dish of water being fixed to a stand and that set on a plate of glass, or on the brim of a drinking-glass, previously chafed, or otherwise warmed), I have found, upon trial, that the same thing happened to all bodies without exception, whether solid or fluid, and that for that purpose 'twas sufficient to set them on a glass stand slightly warmed, or only dried, and then by bringing the tube near them they immediately became electrical.

I made this experiment with ice, with a lighted wood-coal, and with everything that came into my mind; and I constantly remarked that such bodies of themselves as were least electrical had the greatest degree of electricity communicated to them at the approval of the glass tube." His next important discovery was that colors had nothing to do with the conduction of electricity.