the one a vegetable Salt wholly dijfolvahle in water : the o- 
therfo ftubborn,that feveral very corrolive7lf^w/?r«awj, that 
will eafily diffolve Iron and Cofper ^nd Szlvar and almoft 
any thing, will not make any Imprellion here. The one 
aftords a little volatile Salt, which is Alcali^at, and no 
fixt Salt, The other gives no volatile Salt, and a very 
large proportion of fixt. The one affords much more 
earthy Subjiance c^U'd Terra Damnata than the Hoofes 
ot Horns of Animals, ^c, and the other leaves usfcarce 
any. One abounds with 2iW acid Salt, which is fenfible 
to the palate, and very manifeft in the iS^m> of Tartar, 
but in the other we could difcover none upon the nar- 
rowed fearch. This leads us to the Examen of Tachenius 
his Experiment : which is this. 
He puts a whole Stone of the Bladder into a Retort, 
and diftils over a liquor, which he acknowledges to be 
urinous; this done; he pours back the liquor upon the 
body from whence it was diftill'd, which he fays reduces 
this Caput mortuum after a fhort infufion to its former fo- 
lidity. From whence he concludes fome occult Acidm\yX 
with this Alkali, muft needs caufe the hardening fo friable 
a body, which, without it, will be apt to crumble into duft 
like the Subterraneal Car\a^es of l^me, that molder away 
upon the leaft touch. 
A great fondnefs iottht Hypothefis made the Opera» 
tor very carelefs in his Examination. For the Caput 
mortuum he fuppofes fo very pulverifable, I could never 
find fo, but aitzt Biftillation it remained almofl: as hard 
as formerly, and this is certain that upon the Reaffufion 
of the Spirit, it grew rather fofter than harder. But if 
we refled: upon what has been faid and experimented be- 
fore, it will prove unneceffary to argue further againlt 
Tachenius, Hence we may infer that 'tis very dangerous 
to give the fame names to things that are very oppofite 
in their Natures : by this means men are very apt to be 
led into Errors. Thus the notion of prefuming this mat- 
ter 
