thaS ofthc two other Satellits, together ivkh their periods^ ai 
grees bcttclr with 80 days. Therefore intheEpiemrid which 
we give of one RevolutioD , we follow this/ untill we get a 
moreprccifedetermiuatioos which requiresa greater number 
of Obfcrvatioos, that cannot be begun but towards the next 
fuminer Soffticejby realbn of the Oblique Afcenfion ofSaturn^ 
and his Southern latitude, which will keep him long in the 
beams of the Sun. 
An Extra^ of a Letter^ Written ^/ David von der Bccke ^ j 
German Fhilofipher and Phyfftian at Minden, to Do8or Lan* 
gclott, Chief Phjpian to hk Highnefs theDuke ofliolSttin 
now Regent^ cpncerning the Principles and Caufes of the Sfoldi^ 
iMmQnof^^XtolXzxmandotherFixedSalts.^ Printed at 
Hamburg, 1672. 
THfs Learned Author, having exploded thctlfelefsaqd 
Empty terms of Faculties^ ^alities^ and recom- 
mended the InvcftigationofNature by guided ^b^ 
Reafon 5 commends, for the praftice of this latter, that ex- 
cellent Naturalifl: and Phyfitian, Dr. Joel Langelottj in that 
Difcourfe of hisj touching the great Ufc of Digefiion^ Fer-' 
mentation^ and (?riWi»g in Chimiftry 5 of which a Breviate 
was given in NumkBj, of thefe Trads* Out of which Dif^ 
courfe he chufetb,before all,to elucidate that part, which treats 
oUhc Folatilifation of Salt (f Tmar^^^^^ which he 
had likewifc confidered and inquired into. 
Having therefore; (as he affirms , and as will appear by 
thefequelj) formerly taken pains in the like Fermeotation of 
Tartar for the Volatilizing the Fixt Salt thereof^he endeavours 
here to declare his thoughts about thtCaufes of his undertaking 
that labour, and of the Manner how that Volatilifation is per- 
formed. In the tloipg of which he labours to (hew, firfi.The. 
Caufes of the Fixation of the Salt of Tartar : Secondly , The 
Reafinf of the Volatilifation i And I'^f/il/y what degree of Vola^ 
tititjf the Salt of Tartar hath acquired in that Fcrmcntatioa 
made with its own Ferment. 
As to the firji, he begins with bkming thole , that divide 
Zzzz z % Salt 
