1823.5 Scientific hitelligencb, 5§S 



it rests itntnealately on granite, and at the Muckish mountairt 

 contains a bed of pure siliceous sand of considerable thifckness. 



The author proceeds to notice the ancient beaches of Jur^ 

 which appear hitherto to have escaped observation : these occur 

 on both shores of Loch Tarbert, and are disposed in six or seven 

 terraces rising regularly from the present shore, above which the 

 highest is elevated about 40 feet ; the breadth occupied by these 

 beaches, in some instances, amounts to three-fourths of a mile, 

 and their line or extent has been traced eight or teh miles. 



The author concludes with a description of, and remarks on, 

 the trap dykes of Jura ; these are extremely numerous, and 

 Remarkable for preserving courses nearly parallel to each other, and 

 nearly in the line of dip of the quartz rock which they traverse, 

 which gives occasion for offering some reasons to account for 

 that particular disposition. 



Article XV. 



SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS 

 CONNECTED WITH SCIENCE. 



I. Composition of Morpliia, 



From the experiments of M. Bussy, it appears that morphia is com'« 

 posed of 



Carbon 690 



Azote » i »...*..., i ..... . 4*5 



Hydrogen , Q'5 



Oxygen * .. ...4 i»6i . ; ». . . 20-0 



100-0 

 (Journal de Pharmacie, viii. 590.) 



II. Corrections for Moisture in Gases. 



The following observations and formulae are taken from the last 

 edition of Dr. Henry's Elements of Chemistry, vol. i. p. 25 : — 



Another correction, which it is often necessary to make in taking 

 the weight of gases, is for the quantity of aqueous vapour diffused 

 through them. It is obvious that all gases, which are specifically 

 heavier than aqueous vapour, must have their specific gravity dimi- 

 nished by admixture with steam ; and, on the contrary, all g^ses that 

 are specifically lighter than steam must have their specific gravity 

 increased by that admixture. For the following formulae, I am indebted 

 to Mr. Dalton, who has obligingly stated them at my request. 



'* At ordinary temperatures, the tension or elasticity of aqueous 

 vapour varies from 1-lOOth to l-50th of the whole atmospheric pres- 

 sure ; in the present case it is supposed to be a given quantity. The 

 specific gravity of pure steam compared with that of common air, undeir 

 like circumstances of temperature and pressure, is, according to Gay- 

 Lussac, asO*620 tol. 



" Let a = weight of 100 cubic inches of dry common air, at the 

 pressure 30 inches and temperature 60° Fahr. ; p = any variable pres* 



