Chemistry and Physics. 131 



read off. By this means the value dT/dp is obtained, in Profes- 

 sor James Thomson's equation for the variation of the fusing 

 point with pressure 



dT T ff-r 



— = 10333 . =, . 



dp iL r 



in which T is the fusing point, p the pressure, ff the specific vol- 

 ume of the liquid, r that of the solid, both at the melting point, 

 and r the heat of fusion at the melting point. The author deter- 

 mined the values of dT/dp, T, ff, ff-t and r for acetic acid and 

 also the value (<7-r)/r directly by means of an acetic acid calori- 

 meter. For the melting point of this acid T at 760 mm he finds 

 16*6713° by the mercury thermometer and 16*5965° by the hydro- 

 gen thermometer. For the density of the liquid at the melting 

 point, he obtains 1*05315 compared with water at 4°; and hence 

 the specific volume 6 is 0-94953. Since the change of volume on 

 fusion of one kilogram in cubic meters G-r is 0*00015955, the 

 specific volume of the solid at its melting point is 0*78998 or its 

 specific gravity is 1*26585. The heat of fusion at the melting 

 point r was found to be 46*416 calories. The calculated value of 

 (<J-r)/r was 0-0000034374; that found directly being 0*0000034425. 

 The value of dT/dp as calculated was 002421° as compared with 

 0*02435° found with the manocryometer. 



The author has also described an interesting lecture experiment 

 with the manocryometer. A tube of 2 mm interior diameter hav- 

 ing walls 6 mm thick, is sealed off at one end and drawn out to a 

 capillary size at the other, the whole being about 15 0m long. 

 This tube is immersed in pure acetic acid and filled by alternately 

 exhausting it and plunging its open end into the acid. It is then 

 inverted and the capillary end being plunged into acetic acid, the 

 wider end is cooled by surrounding it with cotton wool on which 

 ether is dropped. The acid in the tube solidifies with consider- 

 able diminution of volume, fresh acid being drawn into the tube 

 in consequence. When the greater portion of the acid is solidi- 

 fied the capillary end is withdrawn from the acid and the cooling 

 is continued until some air has entered. The end is then sealed 

 and the tube is ready for use. It is now suspended in a beaker 

 of water the temperature of which is gradually increased. At 

 the ordinary pressure acetic acid melts at 16*6° ; but when it is 

 thus confined in a closed space, it creates a greatly increased 

 pressure as it melts, and thereby raises the melting point of the 

 remaining solid. In this way the author has succeeded in raising 

 the fusing point as high as 40° corresponding to a pressure of 

 about 100 atmospheres. When, these tubes break they do not 

 explode but crack lengthwise. — Mec. Trav. Chim., xii, 201, 154 ; 

 J. Chem. /Soc, lxiv, ii, 563, 566, Dec, 1893. g. f. b. 



3. On the Fusion and Volatilization of Metals and Oxides in 

 the Electric Arc. — In continuing his researches on chemical reac- 

 tions at high temperatures, Moissatst has exposed various metals, 

 salts and oxides to the heat of his electric arc furnace. To con- 



