VOL. XI.] PHILOSOPHICAL TRANSACTIONS. 36/ 



according to the prevalency of the lighter or heavier ingredient in the mixture, 

 the compounded oil would almost totally either emerge to the top of the water, 

 or He beneath the bottom of it; I say almost totally, because some parts of the 

 oil, which was not perhaps all uniformly mixed, did not keep in a body with the 

 rest; but either was separated from the mass in the form of globules, or else 

 sticking to the side of the glass, had the other part of its superficies, which was 

 contiguous to the water, very variously figured, according as the bulk and de- 

 gree of gravity of the adhering oil and other circumstances happened to deter- 

 mine. And it is chiefly on account of this various and odd figuration of our 

 mixture, that I here mention this trial. 



These are some of the phienomena I observed in oil of turpentine, when it 

 was environed only with fluids; but, when permitted to be contiguous to the 

 inside of the glass, and so to fasten part of its surface to a solid, the greater 

 part of the surface which remained exposed to one or both of the contiguous 

 liquors, would partly by their action, and partly by the gravity of the oil itself, 

 be put into figures so various, and sometimes so extravagant, that it was much 

 more pleasant to behold them than it would be easy to describe them ; which 

 therefore I shall not here attempt to do. 



When the oil of tartar or nitrous alcali, happened to be very clear and colour- 

 less, I have sometimes made highly rectified spirit of wine float upon it, so that 

 in most positions the phial seemed to have in it but one uniform liquor. 



Taking deliquated alcali, made of nitre and tartar, and deeply tinged with 

 cochineal ; and that the liquors might not only be heterogeneous, but as differ- 

 ing in gravity and density as we could make them, we poured on it a peculiar 

 kind of oil lighter than spirit of wine, and holding the plain where the two 

 liquors were contiguous in a convenient position, in respect of the light and the 

 eye, I observed it to make a strangely vivid reflection of the incident beams of 

 light : so that this physical surface, which was flat, looked almost like that of 

 quicksilver ; and the bright figure of the flame of a candle was strongly re- 

 flected almost as from a close specular body. 



To these phaenomena I shall add another, which is, that though pure spirit of 

 wine be so thin a liquor, and our oil is so light as to swim upon it ; yet I found 

 the confining surface very strongly reflexive. — I found also that some other 

 essential oils, and particularly an unsophisticated oil of lemons, did with our 

 tinged alcali, afford most of the same phaenomena; but not so brisk a reflection: 

 I say most chiefly, because with spirit of wine these subtile oils, as I formerly 

 noted, v^^ill readily be confounded. 



