Benjamin Franklin Papers

To Benjamin Franklin from Cadwallader Colden, 28 October 1751

From Cadwallader Colden

Draft: New-York Historical Society

New York Octr 28th 17517


I had the pleasure of receiving yours with the favour of a copy of your Electrical experiments. My being in this place prevents my reading them with that attention which they deserve and which I intend to do assoon as I shall return home. My Notions on Electricity are confused and indigested. I know not wherein consists the difference between an Electric body per se and a non-electric or why one is an Electric and the other a Non electric. Without knowing this it will be very difficult if not impossible to account for the Phoenomena or to understand any reasoning on the Phoenomena. In the time I have been allowed amidst perpetual avocations to think on your experiments they seem to me to lead more directly to the discovery of the cause than any set of experiments which I have seen. But I suspect that the air surrounding Electrics and Non electrics has not been sufficiently considered. May not many of the Phoenomena arise from the air on the opposite surfaces of electric and non electric bodies. I suspect that the Phoenomena of angular and pointed bodies arise likewise from the air which surrounds them. I am apt to conclude that electrical experiments made in Vacuo may be of use not only for discovering the true cause of Electricity but likewise the cause of the elasticity of the Air. For example what are the Phoenomena when the air is exhausted from the Water contained in the phial before it is charged. Whether the electrical atmosphere extends farther or less in Vacuo than in the air. Whether a point will draw it off at a greater distance or otherwise. Whether the electrical atmosphere extend in proportion to the density of the surrounding air or reciprocally to the density. I fancy that if experiments of this kind were well contrived they may lead us a great deal farther in discovering the cause of electricity and the laws of its action than we have as yet got. But it is probable you have allready made experiments of this sort and that I only discover my ignorance in proposing them. However I shall be much obliged to you by your giving me your Sentiments on what I write that I may not indulge my self in a vain and fruitless speculation. We have no means in this place of making the experiments which I propose. If such have not been allready made I am perswaded no man is more capable of contriving and executing proper experiments than your self to discover whether a thin plane or surface of air lying between an electric and Non electric or contained in them be not differently affected on the one side and the other. It is evident that the success of electrical experiments is different in different dispositions of the air and therefor it may be concluded that the air acts a considerable part in produceing the Phoenomena.

[Note numbering follows the Franklin Papers source.]

7Incorrectly dated 1757 in Colden Paps., IV, 207.

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