6io On the Effe£is of 'Terra 'Ponderoja. 



" There are diflFerent kinds of Spars ; as to 

 " their internal qualities, fome, if taken inwardly, 

 " will vonnit and purge moft violently, as that 

 " in the Lead Mines near Andlefack, in Lanca- 

 ** fliire y and this no doubt confifts in great 

 ** meafure of Salt and Sulphur, which I take to 

 " be the reafon that it is emetic. But the na- 

 " ture of this Spar will more fully be made out 

 " from the fubfequent inllances, and the firft is 

 " by calcination, in which you eafily difcover 

 " that a pound of this will yield adrachm oiArfenic 

 " at the leaft, lying between the lamellae of the 

 *' Spar. Whence therefore this comes to be of fo 

 " poifonous a nature is plainly evident^ notwith- 

 ** Handing this, the neighbours thereabout will 

 " frequently take a fcruple at leaft of this in fits of 

 ** t\\t Jlone, in whom it vomits, purges and works 

 *' violently by Urine ; in this cafe as they have 

 *' frequently aflfured me they have found great 

 ** relief; whence the vomiting and purging 

 ** proceed is evident as we have before obferved, 

 " viz. from the Arfenical Sulphur ; as likewife 

 <* from that profufe quantity of Urine, which 

 *' may fufficiently hint to us v/hat kind of mor- 

 ** bific matter it is that caufes the Diabetes, 

 " both in the quicknefs of its poifonous quality, 

 " and likewife the fweetnefs of the Urine. 

 " There are fome who have ventured to be fo 

 " daring as to take a drachm of this, particularly 

 *' one James Barns's wife and child, but, alas ! to 



'^ their 



