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246 March 25th 1847 It is mentioned by count Rumford in the Journal of the Royal Institution, that the Introduction of balls of fine clay into a coal fire increases the heat, though the clay cannot enter into combustion and thus increase the heat. The idea at first struck me as ridiculous, but on reflection, I found that there was a clear physical analogy to support the probability of the truth of the fact, namely the increase of light which is produced when a solid substance is introduced into the feebly luminous flame of a spent lamp. To test conclusively the truth of the proposition, I put the thermo electrical apparatus in order and deflected the needle of the galvanometer by the heat of a spent lamp, to the amount of 15 degrees, the end of a [[indented for figure]] platinum wire of about six [[/end indent]] inches in length was then coiled into the form of a spiral and plunged into the flame of the lamp, the luminosity was of course considerably increased, while at the same time, the needle of the galvonometer moved from 15 to 27 degrees. The truth of the proposition is therefore conclusively proved by this experiment. But was is the cause of the phenomenon? is it due to the fact of the increase of the combination of the oxygen and hydrogen by the action of the platinum on the principle of the action of the flameless lamp, or is it the result of te conversion of heat of less radiating power into heat of greater. for a notice of Davy's new views of flame, see Bland, Vol 2, page 126 1817. The heat of flame may be diminished by in increasing the light. [[end page]] [[start page]] [[top margin]]March 26th 1847 247[[/top margin]] [[indented for small figure]] Placed a spiral of platinum wire [[/end indent]] in the lower part of the flame, found the light much less intense than in the upper part, also apparently the reduced heat. The glalvonometer without the platina stood at 19 degrees, with the platina in the upper part of the flame, it stood at about 25, with the platina in the lower part, a little less elevated. This experiment must be repeated. I could not manage being alone to hold the wire in the flame and note the degrees of the galvanometer. When a thin plate of mica, 3/4 of an inch in breadth, was held in the flame, the needle immediately passed from 15 degrees to nearly 30 degrees, the mica exhibited a very beautiful appearance such as I never before noticed. [[indent for figure on left]] It became white hot along the line of section of the outside of the flame and the mica while it remained dark in [[/end indent]] the middle. Showing in a vertical section the hollowness of flame. It would appear from the experiments of to day that the increased amount of radiation is due to the greater rapidity of the combination of the elements of the flame and the oxygen of the air, though the question is by no means settled. I need other substances. Flat plate of platinum foil 1/2 inch wide, effect great, needle of galvanometer passed from 11 to 30 degrees. __ hexcarbonal of lime, effect same. Also piece of glass, not all of the same intensity. Tried sulfate of lime, effect not as great as with platinum, still an increase of temperature was indicated. [[line across width of page]] * This experiment shows the parts of the flame most intensely heated very distinctly and gives us a new analysis of the flame relative to its temperature in different parts. [[end page]]
