432 



Prof, J. Dewar and Mr. H. 0. Jones. 



[Mar. 3, 



standing a sufficient length of time at the ordinary temperature the 

 nickel gradually dissolved again, although it was covered by the excess 

 of liquid. This proved in an interesting manner the ease with which 

 the reaction between the deposited nickel and carbon monoxide is 

 reversible. 



The amount of the nickel deposition was notably greater when the 

 liquid was heated in contact with mercury, so that the use of the 

 Cailletet pump for the examination of the critical phenomena was not 

 practicable. 



Eough measurements of the critical temperature were made by 

 observing the temperature at which the meniscus disappeared and 



Table II. — 'Vapour Densities of Nickel Carbonyl by Hofmann's 



Method. 











Percentage dissociated at 

 atmospheric pressure. 







Pressure 



Percentage 



Temperature 



Vapour 



in mm. 



of nickel 







of bath. 



density. 



of 



mercury. 



carbonyl 

 dissociated. 



In nitrogen. 



In carbon 

 monoxide. 



°C. 













17 



85-6 



67-7 











35 



81-8 



161-4 



0-13 







(Ether) 

 78 



62-6 



217 -8 



11-9 



4-1 at 100° C. 



3 -87 at 100° 



(Alcohol) 









in narrow tube 



in narrow tube 



129 



(Ainyl alcohol) 

 182 



25 -2 

 23-8 

 21 -5 



389 -4 

 365*6 

 349 -0 



79-1 

 85 -7 

 98 -4 



r 76-5 

 \ wide tube 



54 -5 

 wide tube 



(Aniline) 



20- 8 



21- 7 



320-6 

 356 -0 



95*-7 



Practically complete in 

 wide tube. 



reappeared, when a quantity of the liquid was alternately heated and 

 cooled in an exhausted and sealed off piece of glass tube of 2 — 3 mm. 

 bore. The tube was heated side by side with a thermometer in a 

 glycerine bath, and was so arranged that it could be inverted at will. 

 The temperatures at which the meniscus disappeared and reappeared 

 in the course of many repeated observations with different samples 

 of material, ranged between 191° C. and 195° C. 



It appears from the observations made with such tubes that the most 

 reliable results were obtained the first time they were heated, the 

 meniscus being better defined and disappearing more sharply than on 

 subsequent occasions. The blurred effect noticed on a repetition of 

 the experiment is due to a somewhat greater amount of carbon mon- 

 oxide being present. 



