some of the Substances which accompany it, &c. 
From the experiments which I have related, it appears to be 
proved. 
ist. That there exists an affinity between silica and alumina. 
sdly. That there exists a very powerful affinity between 
alumina and magnesia. 
gdly. That alumina shews an affinity for lime; but that 
the said affinity is not so strong as Mr. Guyton had supposed, 
nor, if pure reagents be used, is it to be perceived under the 
circumstances stated by him. 
4thly. That Mr. Guyton was .mistaken in every instance of 
affinity between the earths, excepting in the case of silica with 
alumina, which had been observed before his experiments ; and 
that, in the other cases, he has attributed to a cause which does 
not exist, phenomena that must haye resulted from the impurity 
of his reagents. 
Sthly. That neither the experiments of Mr. Guyton, nor the 
opinion maintained in the letter from Freyberg, are sufficient to 
diminish, in any degree, the value of the assistance mineralogy 
derives from chemical investigation. 
