. [ ^^ 1 



differ from each orlier. Some of them being Cio'rc foluble la 

 the menftruum when very much he ited than when it is compara- 

 tively cold, and others may be foluble in it when little warmer 



than its point of congelation " If then we fay, for inilance, 



" that the congealing point of the folvent is looo- of Fahrenheit 

 " and if the folution is at the t^-mperature of aoDj", we may 

 " conceive one portion of the matters diflblved as held by the 

 " fimple diffolving power of the menftruum, and another as 

 " held by means of its elevated temperature; when therefore 

 " a mafs of this Jcind is allowed to cool very flowly thofe fub- 

 " fiances held in folution by the heat of the folvent will firfl; 

 " feparate, and being formed in a liquid will affume their cryf- 

 " taline form with perfed regularity." — This confequence is truly 

 deduced from the Baronet's hypothefis, but being contrary to 

 fadt difcovers the fahhood^ of that hypothefis, for if any of 

 the fore-mentioned component parts of granite can be fald to be 

 held In folution by the high heat of the folvent, it is furely the 

 quartz ; now the quartz is fcarce ever found regularly cryftallized 

 when forming a component part of granite, as all mineralogifts 

 atteft and is matter of univerfal obfervation. 



But the Baronet continues, " whereas tliofe fubftances which 

 " were held by the menftruum fimply as a fluid, will not fepa- 

 " rate until the congelation of the folvent itfelf takes place, 

 " when the cryftals of the various fubftances will intermix and 



" confound 



