WITH THE MARINE ACID. 363 



*rid particles of the fublimatc, rifmg \yith a Icfs 

 degree of heat, may be collcclcd in the fummit 

 of the vcflcl ; from which ciicumftance a va- 

 cant fpace of fomc inches in length is left in 

 the neck for the pure mcrcurius dulcis, when 

 it is raifed with an encrcafed degree of heat. If 

 a coated vcflcl is expofrd to an open fire, the 

 upper portion of the neck mud be left uncpver- 

 cd for feveral inches. 



The fire is to be gradually augmented, until 

 it be fomcwhat more powerful than in the pre- 

 paration of corrolivc fublimatc. If it is too 

 flrong, Wilion tells us, the fwcct mercury turns 

 black, and retains this appearance with fucli 

 pbilinacy, that fublimation alone repeated can 

 fcarce remove it, unlefs it is feveral times rub- 

 bed with common fait *. 



The veflcls being broken and opened, befides 

 the fwcct mercury, a yellow or afh-coloured 

 powder is found in the receiver ; a few grains of 

 which we are told by Vogel arc AuTicient to kill 

 a dog f . This is the corrofive mercury not ren- 

 dered mild by fublimation. At the bottom of 

 the vcflcl is found a dry and inert mafs, foine- 

 timcs .of a rcddifli colour, which I apprehend 

 to be the rcfiduum only of the extraneous mat- 

 ter adherent in the corrofive mercury ; although 

 Junker confidcrs it as fomething of a peculiar na- 



turc, 



* WJlfon'a courfc of chcmi&ry, 1699. 

 f Inftit. Chcm. 



