335 



to be quite inert, and to attack neither the compounds studied, nor 

 the thermo-elements. Carhondioxyde can be used as a furnace-atmos- 

 phere up to relatively liigh temperatures, but is often not very suit- 

 able to be bubbled through molten salts under these circumstances, 

 because of its character as an anhydrous acid. Furthermore, at the 

 highest temperatures a slight dissociation is always to be feared. 

 At the same time the dry nitrogen permitted us to drive out the 

 air from the glass bulbs at lower temperatures, and completely 

 prevented the oxidation of the organic liquids studied. 



Fig. 1. 



The nitrogen employed was prepared from a mixture of jiure 

 sodiumnitrite and ammoniumchloride, washed by distilled water, 

 and collected in a gasometer D (fig. 1). It was led through a series 

 of wash-bottles e, tilled with an alkaline solution of pyrogallol, then 

 through others, tilled with concentrated sulphuric acid (/). and tinally 

 through a tube ƒ, containing a large surface of freshly sublimed 

 pliosphorous-pentoxide. The dried gas was preserved in a collector W, 

 closed with dry mercury. When needed, it w^as pushed on into a 

 metal reservoir N by means of a movable mercury-holder Z. Any 

 arbitrarily chosen pressure could lie used which was then read on 

 the mercury-manometer A. The stopcock E carries a micrometer, 

 used in the regulation of the gas-current. In the study of the organic 

 liquids, this reservoir N was placed in the oil-thei-mostate U, with 

 the glass-bulbs containing the liquids to be investigated. In this way 

 the nitrogen was pro-heated to the tempera! ui'e of observation, thus 

 preventing disturbances of temperature in the surface-layer of the 



