[M4] 
To deviate a litde, though not from a Propofition made 
before the Royd Society^ which was to endeavour what we 
could, to reduce bodys to fuch fetled Standards, as might 
^ fomewhat reprefent their Natures, and free us from falfe 
and confufed Conceptions of Things^ or give us an account 
offome bodies, whole Natures we. are doubtful of In a 
finall Treatife of the Cdcdus hhmmus^ I found reafbn to 
complain of the Impofition of our Senles upon our Con- 
ceptions in calhng that a Stone by its*external appearance, 
when it has no real properties of a Stone. I have alfo, in 
this, Reafon to except againft Chdke^ ( commonly taken for 
a Stone ) for being brought to the Hydrofiaticd Examen^ ( if 
that may be allowed as a Standard ) it wants much of the 
true Confiftence of a Stone, as the Calculation mentioned 
does manifeft. For it wants much of that weight, which 
real Stones are prcfved to have in Water, and it may per- 
liaps be better reckoned amongfi: Boles than Stones. I found 
this true, not only in Chalk, but various other bodies taken ^ 
for granted to be Stones at large : feme of which are nearer 
Earths than Stones^ others have nothing but Earth and 
Sdphur md Metdl, and yet muft be called Stones, (as all 
Marchafites are. ) Of thefe the former, ( namely the Boles ) 
many of them fall fhort of our Standard, others are more 
ponderous and fb exceed our Standard, whereas zymq Stones 
though differing much in hardnefs, whether Pebbles, Flints, 
petrifyed Waters, &e. do anfwer the lame Standard of Spe-^ 
cifick gravity that a Diamond does. But that thefe natural 
bodies fliould as exaftly agree, as Metalls do, when they 
are by art feparated from ail Heterogeneity^ cannot beex- 
peded in Compound Bodies, though I doubt not but much 
ufe may be made of it by thole that are more accurate: 
