360 



ANALYSIS 01 ALUM ORES. 



Native. 



At Cape 

 ?Iiseno. 



obtained from rarious earths and stones, which contain thd 

 elem(ints necessary to its formation in a more or less perfect 

 state, and are included under the name of alum ores. Thus 

 the alum of the shops is an artificial production. 



Nature it is true presents us with alum completely formed 

 in some volcanic countries, but it is in so small a quantity, 

 as to be altogether insignificant compared Avith the great 

 demand for it. Among the native alums of volcanic coun- 

 tries that of the alum grotto at cape Miseno, near Naples^ 

 is particularly to be distinguished. This is continually 

 efflorescing on the inside of the cavern in small tufts, com-, 

 posed of little, short filaments of a silky lustre, sometimes 

 intermixed with granular crystals. From the results of my 

 examination, which have been published some years, it is 

 well known, that the greater part of this native salt is a 

 perfect alum, that is to say, it has from nature not only 

 the sulphuric acid and earthy base, but likewise the third 

 essential constituent principle, potash. 



It appears, that the alum we now use was not known to 

 the ancients; and that the alumen of the Romans, as well 

 as the s-i'Trln^ta of the Greeks, was a native sulphate, arising 

 from the decomposition of pyrites, and consequently not 

 differing from their misy and sory. 



The art of extracting and preparing alum came to us 

 from the Levant. The most ancient of the alum works 

 known to us is that of Rocca in Syria, now called Edessa; 

 whence the term alumen Roccce, vulgarly rock alum. All 

 the alum used in Europe in the middle ages was brought 

 from the Levant. 



In the fifteenth century some Genoese, who, had learned 

 in the Levant the mode of fabricating it, were fortunate 

 enough to discover ores of it in Italy, and to extract it 

 frono them. John of Castro is recorded in history as the 

 Holly abundant first, who discovered the ore of Tolfa. To this discovery 

 he was led by the large quantity of holly growing there; 

 as he^ad observed in the Levant, that the mountains from 

 'w>.ich alum was taken there were covered with this shrub. 



The manufactures of this salt succeeded so well and so 

 speedily in Italy, that pope Julius II prohibited its impor- 

 tation 



Alum of the 

 ancients. 



First made in 

 the Levant. 



Roch alum. 



Introfluced into 

 Italy, 



on a luminous 



