160 DR. R. ANGUS SMITH ON A 



He then tells of Kratzenstein's measurements, and re- 

 sumes at 203 : — u This is my mode of observation. I have 

 a sort of eolipile made with two bulbs — a tube of glass 

 sealed at A and open at D ; the two bulbs C and B com- 

 municate with each other and the opening at the point D. 

 I pass a few drops of water into the bulb B, and put it on 

 the flame of a spirit-lamp. I use spirits of wine, so as not 

 to soil the bulbs of the eolipile. As soon as the water is 

 sufficiently heated in the bulb B, and the bulb C cold, one 

 sees the vapours coming out of B, enter into C, and condense 

 in the form of a cloud which is entirely formed of vesicles. 

 But when the water begins to boil in B, the torrent of 

 elastic vapours which enter C reheats it ; the vapours no 

 longer condense ; we see clouds or vesicles no longer. But 

 take away the eolipile from the flame, and with a little fresh 

 water cool the bulb C ; one sees then immediately a vesi- 

 cular vapour. Under a microscope these vapours may be 

 better observed ; but the rapidity of their movements pre- 

 vents us seeing them with large magnifiers." 



At p. 293, par. 206, he speaks of clouds, and says again 

 "This is my mode of observation;" but it ends simply in 

 looking at the fog with a lens, and waiting till he sees a 

 drop or a particle pass. 



Finding that the thinness of the envelope will not give 

 them qualities sufficient, he, as others before him, seeks 

 some other liquid, and in par. 210, talking of an atmo- 

 sphere rarer than air surrounding bodies, says, ' ( Even our 

 vesicles give a very striking proof of the existence of their 

 atmosphere, and that by the ease with which they roll on 

 the surface of water without mixing or adhering ; for it is 

 evident that if they adhered they would be attracted 

 strongly ." But this is another subject. 



Par. 211. " Is this fluid electricity?" 



In par. 213, speaking of the cause of vesicularity, <c We 

 have no distinct notions of the intimate and elementarv 



