▼OL. XV.] VHILOSOPHieAL TRANSACTIONS. 181 



Secondly, as to its natural principles, though it be commonly by the litho- 

 graphers reckoned among stones, I should rather judge it a terra lapidosa, or 

 middle substance between stone and earth ; but whether the one or the other, 

 it probably consists of a mixture of some salt, and a pure earth without sul- 

 phur, coagulated in the winter, and hardened to maturity by the summer heats. 

 Which salt Johannes Hessus proves, by a very cogent argument, to be alumen 

 liquidum, describing it, as Matthiolus also does, to be a whitish lacteous sub- 

 stance, somewhat inclining to yellow, that sweats out of the earth, and smells 

 like rotten cheese; of which, having gathered a quantity at Puteoli, together 

 with the other species of alum, and kept it a while by him, when he came to 

 look on it again, he found it to have lost the smell, and a great part of it 

 changed into alumen plumeum; the saline part I suppose shooting into threads, 

 and the pure earth uniting them, as found in the places wherever generated 

 whether by sweating from the earth, as Pliny and Matthiolus would have it, or 

 percolated through rocks, as found in Wales, the veins of it there running 

 through a rock of stone, in.hardness and colour not unlike flint. And yet it 

 seems to be made of much such an alum as that of John Hessus, at Puteoli 

 was, some of it being straw-coloured, as if it still retained the yellowness that 

 his liquid bitumen was said to have, which is a colour not assigned to it by any 

 author, most of it being said to be white or cinereous ; some of it red, and 

 some of an iron-colour, asAgricola tells us; and I have some of the Cyprian 

 by me, sent from Aleppo by my worthy friend Dr. Robert Huntington, part of 

 which is of a light blue or pearl-colour, and some of it has a cast of sea-green. 

 But however the whole mineral substances found at several places may differ in 

 colour, yet I do not find but the woolly part of them all seems to be much the 

 same, viz. of a white silver colour, the threads very fine and slender, yet very 

 ponderous, the smallest particles of them, when thoroughly wet, sinking in 

 water; whence it is probable, that it is not a vegetable but a mineral substance, 

 although it be known that there are several woods, such as box, red wood, 

 Persian wood, &c. that will sink in water. 



Concerning the manufacture of it into thread, cloth, &c. Marcus Paulus 

 Venetus acquaints us, in his book de Regionibus Orientalibus, how it is made 

 in Tartary; where he says it is found in a certain mountain in the province of 

 Chinchinthalas, and made into cloth, as he was informed by one Curficar, a 

 Turk, superintendant of the mines in that country, after this manner. The 

 lanuginous mineral or amianthus being first dried in the sun, is then pounded 

 in a brass mortar, and the earthy part separated from the woolly, which is after- 

 ward washed from any impurities that may stick to it; being thus purged, it is, 

 then spun into thread like other wool, and after wove into cloth, which when 



