Chemistry and Physics. 147 
them. This subject has recently been investigated by Sir William 
Thomson, who has given full details of his result in a remarkable 
paper in “Nature” vol. i, p.551. Sir William says the diameter 
of the molecule cannot be less than z59,54y,a57 Of a centimeter. 
The number of molecules in a cubic centimeter of a liquid or a 
solid may, he says, be from 3X10" to3X10*. This gives the dis- 
tance from center to center of two consecutive molecules to be 
aaivsor of a centimeter. Now, if we take 
theory appears therefore to be utterly irreconcilable with Sir 
But even supposing we were to assume, what we are ha ar- 
ranted in doing, that the molecules are 10,000 times smaller and 
their distances 10,000 times greater than Sir Willi omson 
concludes, still this would not assist the or c 
Mag., Jan., 1878. : 
10, On the Thermal Conductivity and Diathermancy of Air 
and Hydrogen.—Dr. Henry Borr, Professor of Physics in the 
University of Giessen has undertaken the revision of the wo 
rong eeigp Tyndall and others upon this subject. The apparatus 
could be filled with any gas at any pressure. A thermometer was 
luserted through a tubulature about 50 mm. below the thin glass 
plate placed in a horizontal position. e upper vessel was filled 
ed 
he found that the temperature akeny"s pyoabad ie: , 
even at ordin atmospheric pressure it had greater dlatherman 
than a ane He batt “8 ly concluded that hydrogen was 
Similar to the metals in to conducting power. Dr, Buff’s 
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