630 REPORT— 1903. 



with the observed facts. Fluoran, thouc^h not itself tautomeric, might give tauto- 

 meric fluorescent oxonium salts ; these have been isolated. The non-fluorescence 

 of the nitro- derivatives of fluorescein is readily explained; the nitro- groups enter 

 into the ortho- positions to the hydroxyl groups, and since compounds of the type 

 — C(NOo) = C(OH) — yield sodium salts wliich are, in all probability, of the general 

 formula— C(NO.,Na) — CO — the fluorescence -wliich depends on a doubly sym- 

 metrical tautomerism is necessarily inhibited. 



Whilst in the greater number of cases the theory propounded agrees with the 

 observed facts, exceptions such as the following must not be overlooked. 



1. Substances having the necessary constitution, but not exhibiting fluorescence. 

 A secondary tautomerism might inhibit the vibration between two extreme 



similar configurations ; this case has been considered in dealing with the nitro- 

 derivatives of fluorescein. 



In some cases it is possible that fluorescence has not been detected owing to 

 the emitted radiant energy corresponding to an invisible part of the spectrum. 



Another cause which may preclude the necessary vibration is that the sym- 

 metrical intermediate configuration may correspond to more molecular free energy 

 than the extreme unsymmetrical configurations. The molecule would then have 

 no tendency to vibrate regularly, the case being analogous to that of an inverted 

 pendulum. 



2. Substances which fluoresce but cannot possess doubly symmetrical tautomeric 

 formulas. 



The author does not think the occurrence of such substances can be taken as a 

 serious argument against- his theory, which may be formulated as follows : 



If the molecules of a tautomeric substance possess such a structure that the 

 passage from the configuration of least free energy to the less stable configuration 

 may be eflected by equal and opposite atomic displacements, the molecules will 

 vibrate between the extreme positions and the substance exhibit the phenomenon 

 of fluorescence. 



That fluorescence may be due to other causes is not negatived by this assertion. 



3. Preliminary Note on some Electric Furnace Reactions under High 

 Gaseous Pressures. By J. E. Petavel and R. S. Hutton. 



The paper gives an account of some work carried out in an inclosed electric 

 furnace constructed to work with gaseous pressures up to 200 atmospheres. 

 The power employed has been usually about 15 kilowatts per hour, the furnace 

 containing a charge of about 20 lb. of material and 1,000 to 2,000 litres of gas. 

 A second furnace of about one-tenth the capacity was used for gas reactions with 

 high-tension current. 



The reactions at present under investigation include the direct reduction oi 

 alumina by carbon, the conditions of formation of calcium carbide, particularly as 

 modified by the change of gaseous atmosphere, and the formation of graphite. 

 With regard to gaseous reactions a study of the production of nitric acid and 

 cyanogen compounds has already been commenced. 



The preliminary experiments have shown that under pressure alumina is 

 reduced to the metallic condition, but in all cases accompanied by a large amount 

 of aluminium carbide. This reaction is most unfavourably influenced if the carbon 

 monoxide which is formed be retained, whereas it is favoured by the rapid removal 

 of the gaseous products of reaction. So far as calcium carbide is concerned, 

 contrary to expectation, the yield is in no way diminished by the presence of 

 carbon monoxide gas even at high pressures. An important difiierence in the 

 methods of working is necessary in those cases where it is desired to efl'ect purely 

 gaseous reactions. Here a high-tension current is required. For instance, the 

 formation of nitric acid, even at pressures of 100 atmospheres, is only accomplished in 

 appreciable amount where the electromotive force used is of several thousand volts. 



The account includes a general description of the plant employed for preparing 

 and compressing the various pure gases required in quantity for this work. 



