TRANSACTIONS OF SECTION B. 577 



toth consist of three distinct bands or groups of bands: those produced by tbe 

 uranous salts are at the red end of the spectrum, and those produced by the uranic 

 salts at the blue end, the one set of bands beginning where the other set ends, so that 

 •when both salts are together in solution there are a series of bands visible which are 

 distributed with tolerable regularity over the whole visible spectrum. Nine uranic 

 salts, some organic some inorganic, have been examined, and it has been f lund that 

 allgive the same spectrum, that is, the spectrum is unaffected by the acid radicle. 

 "With other metals, such as cobalt for instance, this is not the case, diiferent radicles 

 producing different spectra. This spectrum, common apparently to all uranic salts, 

 is however slightly altered by the addition of free acid, the acid causing a diminu- 

 tion of intensity in the least refrangible bands, and causing an apparent slight shift 

 in others. Crystals of the uranic nitrate give an absorption spectrum similar to 

 that produced by an aqueous solution of this salt. 



The uranous salts give also in all cases examined a common spectrum, and one 

 in which all the bands are less refrangible than those belonging to the uranic salts. 

 The authors have also examined a few of the uranous salts in the solid state, and 

 find that these salts have then a far more complicated spectrum than when in 

 solution. 



The Air of Bioellings and Schools, and its relation to Disease. 

 By Professor T. Carnellet, D.Sc. 



3. On some prohahle new Elements. By Alexander Pringle. 



4. On the Action of Bromine on the Trichloride of Phosphorus.^ 



By A. L. Stern. 



After a short historical introduction experiments were described in which phos- 

 phorus trichloride and bromine were mixed in various proportions; in all cases 

 a considerable quantity of heat was evolved, and when sufficient bromine was 

 present crystals were dej osited on cooling ; on analysing these it was found that 

 the amount of bromine present at any given temperature was proportional to the 

 amount of bromine present in the mixtures, also that those crystals which contained 

 the most bromme were the least stable ; at a temperature of 10° C. it was possible 

 to obtain a compound containing ten atoms of halogen, while at 35° C. the compound 

 PCljBrj was decomposed (MichaeUs). 



It w'as also found that bromine replaces part of the chlorine of the trichloride, but 

 not much more than half even when such a large excess was present as twelve 

 atoms of bromine to one of the trichloride ; Gladstone, however, found that in the 

 presence of a smaU quantity of iodine all the chlorine of the trichloride may be 

 replaced by bromme and the penta-bromide formed. 



The constitution of these compounds was then discussed and it was sugoested 

 that they are merely compounds of phosphorus with varying proportions of\alo- 

 gen, and not molecular compounds ; the number of atoms of halogen with which 

 one atom of phosphorus can combine being an inverse function of the temperature. 



5. Dissociation and Contact-action? By the Rev. A. Irving, B.Sc, B.A. 



The author refers to a letter of his which appeared in ' Nature ' on March 25 last 

 in which he suggested that the true explanation of the many instances known of 

 contact-action of soHd bodies in facilitating combination of gases, which under 

 ordinary conditions and in the free state are chemically inert to one another, was to 

 be found in the transformation of a portion of the energy of translation of the 

 molecules into intramolecular work, producing [ot tending to produce) dissociation 

 as a preliminary to chemical change. 



'_ Printed in full in Jovrn. Chem. Soc, 815, 1886. 



- Published in extenso. Chemical News, October 8, 1886. 



^ . 1886. p p 



