TRANSACTIONS OF THE SECTIONS. 81 



On the Uetent'ion of Ovfjanic Kitrogen h>j Charcoal. By E. C. C. Stanfoed. 



Improvements in Chlor'imetry . 

 By John Smyth, Jun., A.M., M.I.C.EJ., F.M.S. 



The author showed that the use of the milky solutiou of l)leachiDg--po'wder in 

 chlorimetry is unsatisfactoiy, aud was therefore giad to discover a method of securing 

 a clear solution containing all the chlorine by dissolving the sample in an alkaline 

 solution. This is conveniently done by adding, say, 10 grammes of bleaching- 

 powder to 20 grammes of soda-crj'stals (Naj OO3+IOH2O), filtering out the 

 precipitated carbonate of lime, which is known to be washed when it no longer 

 discharges the colour of dilute sulphate of indigo, and making up the filtrate by 

 water to one litre of fluid. It is a clear colourless liquid of the sp. gr. 1'007, but if 

 made of sp. gr. 1'233 it is slightly greenish, having a pleasant oily feeling between 

 the fingers, contrasting favourably with the roughness of the decanted solution of 

 the bleaching-powder, with which it gives a precipitate. Most satisfactory results 

 are obtained from it by all the chlorimetrical methods ; and it has the additional 

 advantage of showing the amount of lime in the sample, a solution of known 

 strength of carbonate of soda being added until a precipitate is no longer formed. It 

 is manufactured and used in the north of Ireland for bleaching fine linens ; and from 

 the ease and accuracy with, which the percentage of chlorine was obtained, the 

 author was led to investigate the feasibility of converting bleaching-powder into it 

 for chlorimetiical pm-poses, and obtained the above results. 



Contributions to the History of the Phosphorus Chlorides, 

 By T. E. TnoEPE, Ph.B., F.R.S.E. 



I. On the JReduction of Phosphoryl Trichloride. 



The author has attempted, but without success, to prepare the phosphorus 

 chlorides corresponding to the oxj'chlorides of vanadium discovered by Roscoe. 

 He found that when phosphorus oxychloride was heated -WTith metallic zinc in a 

 sealed tube to a temperature above the boiling-point of mercury, the phosphorus 

 trichloride (P CI,) was produced. It appears, therefore, that the action of zinc at 

 a high temperature on phosphoryl trichloride is sensibly different from the action 

 of this metal on the corresponding vanadium compound ; in the former case the 

 reaction is attended with abstraction of oxygen, in the latter with abstraction of 

 chlorine. 



II. On the Preparation of PhosjjJiorus Sulphochloride. 



The author found that perfectly pure phosphorus sulphochloride may be easily 

 prepared by a reaction analogous to that by which phosphoryl trichloride has 

 long been obtained ; that is, by simply substituting P, S- for P2 0. according to the 

 following reaction, Po S,-t-.3 P Ch = t> PS CI3. 



The materials mixed in this proportion were heated in a sealed tube to about 

 150° C. ; in a few minutes combination was quietly effected, and the entire contents 

 of the tube were transformed into colomless phosphorus sulphochloride, a mobile 

 liquid boiling constantly at 12G° at 770 millims barom. Its' vapour is extremely 

 irritating, but when diluted with air it has an aromatic odour, reminding one of that 

 of the raspberry. 



On the Dissociation of Molecules by Heat, 

 By C. E. C. TicHBOENE, F.C.S., M.IU.A. 



The term dissociation is applied by the author to specify a certain class of plic- 

 nomena somewhat distinct from ordinary decomposition. This latter term is 

 generally applied to any ease of molecular change which has been consummated, 

 whilst dissociation is used to convey a passive but present phenomenon. If this 

 latter is carried far enough, it ultimately results in a rupture, and thus the phe- 

 nomena of decomposition and dissociation are so intimately connected, that they 

 can hardly be investigated alone. 



1871. 6 



