SUMMARY OF CONCLUSIONS. 75 



whatever to the melting point unless equilibrium is reestablished 

 before solidification is complete a condition which rarely obtains and 

 often can not be produced in viscous mineral melts. Especial attention 

 is directed to this because of the importance of the lowering of the 

 solidifying point in the study of solutions, and the possibility of its 

 application to mineral solutions recently suggested by Vogt.* 



(5) Incidental to the experimental work upon the feldspars we were 

 able to establish the fact that there are no differences of density in 

 the feldspar glasses due to the rate of cooling which are greate r than 

 our errors of observation ( 0.001). Also that powdered crystalline 

 feldspars which are free from inclusions and from glass, even when 

 very fine, do not sinter until melting begins ; powdered glasses of like 

 composition sinter readily at relatively low temperatures (700 to 

 goo), depending primarily upon the degree of pulverization. Again, 

 that powdered feldspars when exposed to the atmosphere adsorb 

 moisture in quantities of an order of magnitude equal to those usually 

 quoted in analyses. (Dana's System of Mineralogy, /. c). It is, 

 therefore, altogether possible that the significance of this moisture has 

 sometimes been mistaken. 



*J. H. L. Vogt, loc. cit. 



