PROGRESS IN PHYSICAL CHEMISTRY. 239 



SOLIDS. 



As illustrating the relations between solids and liquids, 

 the observations of Dewar and of Spring are especially 

 interesting. Dewar (55) finds that under a pressure of 

 sixty tons per square inch many solids flow through a 

 narrow tube, and behave as highly viscous liquids, while 

 other solids show no sisms of flowing. The tube used was 

 half an inch Ioiiq: and one-sixteenth of an inch in diameter. 

 Organic and inorganic substances were employed, but no re- 

 lation between the chemical nature of the substances and this 

 property of flowing could be traced. For example, although 

 potassium chloride and caustic soda flow and form a wire, this 

 is not so in the case of sodium chloride and caustic potash. 



Spring's experiments (56) consisted in clamping two 

 cylinders of metal end to end and heating to 200 or 

 400 . In from four to eight hours he found the cylinders 

 became continuous, and if they were originally of different 

 metals, an alloy was formed, it might be for 18mm. in the 

 region of the junction. He concludes from these experi- 

 ments that even below the melting-point there are indications 

 of the liquid state; the velocity of certain of the molecules is 

 as high as the mean velocity of those of the liquid substance. 



Periodic law. — Three inquiries may be noted in con- 

 nection with the periodic law. Topler (57) finds that the 

 volume-change observed when a metal melts -is a periodic 

 function of the atomic weight. Bailey (58) points out that 

 in an " even " series of elements the temperature of decom- 

 position of an oxide is higher the higher the atomic weight, 

 in "odd" series the reverse rule holds. According to 

 Deeley (59) if the density of an oxide be divided by the 

 atomic weight of the contained metal the quotient is a 

 periodic function of the atomic weight. 



Melting-point. — Cohn (28) finds that the melting-point 

 of a ketone, when an even number of carbon atoms is pre- 

 sent in the molecule, is 8° lower than that of the correspond- 

 ing acid, and that if an odd number of carbon atoms be 

 present the melting-point is i4°-i5° lower. He also investi- 

 gates the melting-points of several "odd" and "even" 

 series of substances ; for the substituted malonic acids the 



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