548 Geological Society : — 



The pentachloride which we used gave no reaction with iodide of 

 potassium and starch, and therefore contained no free chlorine ; it 

 gave no precipitate with corrosive sublimate, and therefore contained 

 no terchloride of phosphorus. An analysis of it gave 



Percentage of chlorine =84* 6 7 

 The formula requires. . . 85-13 



In one experiment we diffused into carbonic acid gas* for three- 

 quarters of an hour at about 300° C, and afterwards dissolved the 

 contents of the lower flask in water, and precipitated with corrosive 

 sublimate, with the addition of a little hydrochloric acid. '0175 

 gramme of calomel was obtained. In another experiment (also 

 into carbonic acid) the time of diffusion was two hours, temperature 

 300° C, quantity of calomel obtained *0285 gramme. 



These two results leave no doubt as to the existence of terchloride 

 of phosphorus in the residue after diffusion ; for the reduction of 

 corrosive sublimate to calomel cannot be otherwise explained. More- 

 over, the presence of free chlorine in the diffused gases was shown 

 by the reaction with iodide of potassium and starch. 



GEOLOGICAL SOCIETY. 



[Continued from p. 323.] 



June 17, 1863. — Professor A. C. Ramsay, President, in the Chair. 



The following communications were read : — 



1. "On the Relations of the Cromarty Sandstones containing 

 Reptilian Footprints." By the Rev. George Gordon, LL.D., and 

 the Rev. J. M. Joass. With an Introduction by Sir R. I. Murchison, 

 K.C.B., F.R.S., F.G.S. 



In the introduction Sir R. I. Murchison gave a sketch of the 

 geology of the Tarbatness promontory, which is composed of vari- 

 ously coloured sandstones, having a conformable dip to the N.W. 

 In these strata the authors had found footprints (of animals believed 

 to be Reptiles) similar to those found in the sandstones on the coast 

 of Elgin; and it was therefore desirable to prove whether these 

 rocks really belonged to the Palaeozoic series, or, as some geologists 

 suppose with regard to the Elgin sandstones, to the Trias. In 

 order to solve this problem, if possible, the Rev. Mr. Joass made a 

 careful survey of the coast from Geanies to Tarbatness Lighthouse, 

 and round along the north shore of the promontory to the inlet at 

 Inver, and found a conformable succession between the undoubted 

 Old Red Sandstone of Geanies and the track-bearing sandstone of 

 Tarbatness. 



The Rev. Dr. Gordon gave a description of the various tracks : 

 the smaller kind are referred by him to an unknown Crustacean ; 

 the larger and more definite impressions, however, he considered to 



* If pentachloride of phosphorus be diffused into air, the residual terchloride 

 c ombines with oxygen to form oxy chloride of phosr^horus, which does not reduce 

 corrosive sublimate. 



