NATURAL PHILOSOPHY. 131 



but it must be regarded as the seat of chemical changes going on upon a, 

 prodigious scale, and with inconceivable energy. If the law designated 

 above, that the more enei'getically the chemical action in combustion the 

 more refrangible the emitted light, be translated into the conceptions of the 

 nndulatory theory, it not only puts us in possession of a distinct idea of the 

 manner in which the combustive union of bodies is accomplished, the quick- 

 ness of vibration increasing with the chemical energy, but it also enables us 

 to transfer for the use of chemistry some of the most interesting numerical 

 determinations of optics. 



OPTICAL PROPERTIES OF PHOSPHORUS. 



At the last meeting of the British Association, Dr. Gladstone read a com- 

 munication from himself and Rev. T. Dale, on some optical properties of 

 phosphorus. He said that phosphorus was known to be highly refractive and 

 disfusive. Its refractive index had been determined at 2' 12-5 or 2*224, a num- 

 ber scarcely exceeded by that of diamond or chromate of lead. This determi- 

 nation was made without reference to temperature, and was that part of the 

 spectrum measured indicated. Then* own experiments produced numbers 

 which showed not merely a very high refractive power, but an amount of dis- 

 fusion unknown in any other substance. The disfusive power was nearly twice 

 that of bi-sulphide of carbon, and largely exceeded that of even oil of cas- 

 sia; its only rival was that assigned to chromate of lead, but some doubt 

 seemed to rest on that determination. The determinations of the disfusion 

 of phosphorus, made by persons experimenting, had indicated an amount 

 scarcely exceeding that of bi-sulphate of carbon ; but a difficulty attending 

 the examination of phosphorus would sufficiently explain this. Phosphorus 

 in a liquid condition had apparently never been examined, as difficulties had 

 arisen from its inflammability, and from the action on cement. An exami- 

 nation of the properties of liquid phosphorus showed a considerable dimi- 

 nution of both the refractive and the disfusive power, it not being in direct 

 ratio with the diminution of density. Liquid phosphorus exhibits a greater 

 amount of sensitiveness than had been observed in any other substance, 

 and it was evidently greater at the high than at the low temperatures. The 

 effect of temperature on disfusion could not be accurately determined. A 

 saturated solution of phosphorus in bi-sulphide of carbon was almost as 

 refractive and disfusive as melted phosphorus itself. There was a certain 

 want of clearness in phosphorus which prevented the lines being distin- 

 guished without great difficulty, which did not arise from any opacity, or 

 from the crystalline character of solid phosphorus, or from unmelted pieces 

 floating about; for it occurred in a solution of bi-sulphide of carbon. The 

 addition of phosphorus to bi-sulphide of carbon rendered the spectrum seen 

 through it misty, according to the amount of phosphorus. This was not 

 due to the great refraction, or the great disfusion, or the great sensitiveness, 

 though this had undoubtedly something to do with it. To what was this 

 due? Different specimens of phosphorus differ widely in respect to this 

 property, and it was perhaps connected with some want of homogeneity in 

 the substance. The phosphorus experimented on was generally colorless. 

 It was a curious circumstance that yellow phosphorus cuts off the extreme 

 red ray this being the opposite of what yellow bodies usually did, and was 

 remarkable also in connection with the red modification of phosphorus. 



