Royal Society. 75. 
in the furnaces, that is, in the manner of ordering the iron to be 
made into fteel, or for the extraordinary hardening of the heads 
and bitts of tools, and not in the matter of which they were 
made 5 for both was done 'by boiUng them in molten iron : It 
cannot be doubted but by nucleus ferri mud be meant well purg- 
ed iron, the fame which Ariflotle calls 'iipyA(r{j.zve<r ji<f'nf>oj j for 
why elle Hiould he tell us that wrought iron itfelf may be made 
liquid, fo as to harden again, that is caft again into fow -metal, 
if it was not to explain to us the manner of making fteel, which 
they did probably according to the direction above delivered 5 
that is, not only boil the iron in its own low-metal, or liquid 
iron, but hammer it aUb, and after that quench it in cold water 5 
as to the fteeling of their tools, they boiled them in fow-metal, 
to fuch a degree of hardnefs or temper, as was requiiite, and did 
not afterwards hammer them 5 for which there might be leveral 
reafons5 as nrfl, that it is eafier to work iron than fteel into any 
figure, that being far fofter and more du6lile and loofe 5 again, it 
is certain, that iron by ignition .is fpoiled or corrupted, fo that 
the oftner it is purged, tho' it were fteel, it would the more re- 
lent^ whence the ancients knowing, that in making their tools 
of fteel, they muft confiderably loofen it and make it abate 
of its temper, they therefore firft fhaped them, and then gave 
them a ftrong body of fteel and temper together, and ib had no- 
thing elfe to do but to finifh them on the grind-ftone and hone, 
to fet the point or edge. 
Jl 2)efcnpHon of certain Shells found in the Eaft-Indies 3 by 
M. Witzen. Phil. Tranf. N° 205. p. 870. 
THERE are found on the coafts of Malabar and Ceylon 
certain cockles or fhells, containing a fiili that lives in the 
bottom of the fea, fixt to the body of the fliell 3 and at a certain 
feafon of the year, they caft their feed, which produces a fort of 
matrix of the iize of this long body, Fig. 4. Plate III. which is 
wrinkled like a faufage, abounds in a great number of round cells, 
which are fo many matrices, each producing its little fhell filli; 
which quit not their cells till they are grown to ilich a bignels and 
maturity, as their weight breaks them off and loofens them from 
their cells, and lb from their common matrix, which remains 
faftened to the bottom of the fea, by the great end, the other 
moving about freely in the water; this matrix hath a back of 
a greyilh colour, and the belly is whiter, which is that part that 
is full of cells 3 the fkin which covers it, is very like that of ftock- 
fifti or other dried filh: Fig. 5. rcprelents a ihell found in tha 
"K 2 river 
