Faraday report to Trinity House   5 July 1862

Royal Institution, 5th July 1862.

The impurity in the carbon is well known and has not as yet been obviated. Many attempts have been made to procure a better carbon for electric lamps than that of gas retorts, but the attempt has not succeeded. Neither does inspection enable one to form a judgment, in this respect, of the character of the pieces of carbon sent for service. The globules in the carbons are of a slag, consisting of alumina and silica with a little iron, and they interfere with the character of the light; but from what I understand they ought not to occur very frequently. When they do appear they are very easily displaced by the lightkeeper, who becomes aware of them by the appearance of the light and the noise accompanying it. Their frequent occurrence is an objection which should be recorded, especially now whilst the lamps are under observation¹.

(signed) M. Faraday.