82 KEPOET— 1869. 



On the Action of Phosphoric Chloride on Hydric Sulphate. 

 By Stephen "Williams. 



Dr. Williamson first described this important reaction as the replacement of one 

 molecule of liydroxyl in hydric sulphate by monovalent chlorine, with the forma- 

 tion of chlorophosphoric acid and a body having the formula HCl SO3, which he 

 termed chlorhydrated sulphm-ic acid. The further investigation of this reaction 

 quite confirms Dr. Williamson's observations, but at the same time shows that the 

 operation goes further than was at first supposed ; the chlorophosphoric acid react- 

 ing on the hydric sulphate in the same manner as the phosphoric chloride. The 

 whole operation may be represented in three steps : — 



(1) H.SO^ + PCl, =:P0Cl3+HCl-}-HClS03. 



(2) H.,S0,+P0Cl,=P0,Cl-t-IICH-HClS03. 



(3) H; S0,+P0, C1= HCl S03H-HP03. 



It was also ascertained that the chlorhydrated sulphuric acid, when added to 

 hydric sulphate, breaks up into hydric chloride and sulphm-ie acid (SO,), which 

 explains the apparent contradiction in Gerhardt's statement, viz. that one of the 

 products of the reaction of phosphoric chloride on hydric sulphate was sulphmie 

 acid. 



GEOLOGY. 



Address by Professor Haekness, F.B.S., President of the Section. 



It has of late become the custom to open the several Sections of the British Asso- 

 ciation with an introductory Address. 



This custom I believe had its origin in this Section when the Association 

 met at Aberdeen ; and upon that occasion Sir Charles Lyell made the important 

 discovery of M. Boucher de Perthes of the occurrence of flint weapons with the 

 bones of large extinct mammals in the gravels of the Valley of the Somme tho 

 subject of his opening address. 



In some instances new matter of importance in connexion with geology has 

 furnished materials for this opening address, but more frequently subjects of local 

 interest have supplied the matter for this pm-pose ; and it is in connexion with the 

 latter that I shall occupy for a short time your attention. 



In no portion of Great Britain have we a better development of the series of 

 roi^ks which forms the link between the well-established Devonian formation and 

 the succeeding well-recognized Carboniferous group than in this county. The rocks 

 which form the link I have referred to are known to geologists as the Pilton beds, 

 deriving their name from the locality in Devonshire where they are best developed. 

 These rocks have been made the subjects of investigation by Sir Roderick I. Mur- 

 chison. Prof. Sedgwick, Sir H. T. De la Beche, Mr. Weaver, Mr. Godwin-Austen, 

 Prof. Phillips, and others ; and of late they have been carefully examined by Mr. 

 Jukes, Mr. Salter, INIr. Townshend Hall, and Mr. Etheridge. 



My reason for refen'iug to these rocks is to point out their relations to certain 

 strata which are very well exhibited in the south-west of Ireland, and which occur 

 in a horizon corresponding to the Pilton shales. 



The Irish representatives of the Pilton shales are marked by a mineral aspect, 

 very nearly allied to their equivalents in this country ; and they contain organic 

 remains of a type very closely approximating to such as are found in the Pilton rocks. 



Before alluding to the Pilton beds, I will refer to their Irish representatives, and 

 the rocks upon which these repose. 



In doing so I shall avail myself of the labours of the late Mr. Jukes, and the 

 oflicers of the Irish branch of the Geological Survey, who were for several years 

 engaged upon these rocks. Before doing so I must, however, pay a passing tribute 

 to the memory of one who has so recently been removed from the scene of his 

 labours. 



For more than eighteen years the late Mr. Jukes filled the office of Director of 



