162 Foreign and Miscellaneous Intelligence. 



is added last the same effect takes place ; nor does the ultimate state 

 of things differ, whether the mixture be made gently, or violent 

 agitation be given to it. 



Dr. Hancock concludes that these seemingly strange appearances 

 result from the strong affinity of the essential oil for ether, by which 

 it attracts it from the mixture with alcohol, combines with it, and so 

 forms a mixture essentially lighter than the ether and spirit. He 

 found, by trial, that though the essential oil would not mix with 

 ether if at all adulterated, that with pure ether it dissolves in ever^ 

 proportion. 



A remarkable circulating motion was also observed when 

 laurel-oil and alcohol were brought together. * Take a phial of the 

 laurel-oil, and drop into it at different intervals some rectified 

 spirits of wine, when the most interesting results will be observed 

 to ensue a circulation, presently commencing, of globules of 

 alcohol up and down through the oil, which will last for many 

 hours or for days, (how long is unknown.) A revolving or circu- 

 lating motion also appears in the oil, carrying the alcoholic globules 

 through a series of mutual attractions and repulsions ; the round 

 bodies moving freely through the fluid, turning short in a small 

 eccentric curve at each extremity of their course, passing each other 

 rapidly without touching, but after a time they seem to acquire a 

 density approximating to that of the lower stratum, which appears 

 to be an aqueous portion separated by the ethereal oil from the 

 alcohol ; and this assimilation taking place, the globules, after per 

 forming many revolutions, will fall flat upon the surface and unite 

 with the lower or watery stratum. This experiment was performed 

 with a small phial : perhaps a larger one would render the result 

 more perspicuous*.' 



6. ON THE QUANTITY OF LIGHT REFLECTED BY METALLIC 

 SPECULA AT DIFFERENT ANGLES OF INCIDENCE. (R. 

 Potter, Esq.) 



A paper upon this subject has been read to the Royal Society by 

 Mr. Potter, in which he shews some curious departures in fact from 

 generally received opinions. Sir Isaac Newton has stated, that 

 metallic specula, in common with all other substances, reflect light 

 most copiously when incident most obliquely. Some experiments 

 made by the author, with specula of his own construction, having 

 raised doubts in his mind as to the accuracy of the prevailing opinion 

 on this subject, which accords with that of Newton and of Bouguer, 

 he instituted a more exact inquiry into the proportions of incident 

 and reflected light from specula at various angles of incidence. He 

 used for this purpose a photometer resembling that of Bouguer, and 

 consisting of an upright screen with a square aperture, across which 

 a piece of thin tissue paper was extended, destined to receive on one 

 compartment the reflected light from one lamp, and on another 



* Brewster's Journal, 1830, 48, 51. 



