421

Tuesday March. 23. 1679.

Present the President, Mr Hill, Mr. Aston, Mr. Hally. mr Hooke.

we made a Regulus of equall parts of Antimony & Iron &
found it to weigh in the Air 533 graines and in the
water 457 1/4 whence the specifick grauity is 7 11/103 .
this we found to be very hard but yet brittle and not at
all malleable, the It broke wth. a short graine and very
black or Little Reflectiue. It seemd not very likely to take
any polish. It had noe manner of operation on the
magneticall needle.

This part we melted wth. aequall parts of tin and found a
mixture that Looked pretty white it continued melted
wth. a small heat Little more then Red hot, It broke
into seuerall peices wth. 2 or 3 blows wth. a Hammer, and
the graine of wch. was exceeding fine & close & smooth and whiter
then Both metall . we polished it and found that It held a very
good polish, which gaue a strong reflection. It weight in
water Air was 859 1/2 in water 758 1/4. whence Its Specifique
grauity is as 7 43/485 - we conceiue it may be very vse
full for making specular glasses for Mr. Newtons Expt.--

Then with another part of the Regulus of . . . . . . Anti=
mony we mixed ^/an/ aequall weight of Lead which soon Incor
porated together. the Result was that It made a compo
sition very hard and & very brittle. It weight in air was
422 6/8 in the water 365 5/8 whence its specifique
Grauity must be as 7 182/457.--

Ref: CELL/RS/HF_423  © Centre for Editing Lives and Letters