[ 74 3 
Surface of the Egg, it will be called the Fird, and 
will be that with which they begin their Operation 
or Boiling. But this way of trying has not all the 
Exadnefs which can be defired, becaufe all Hens Eggs 
have not the fame fpecifk Gravity. Befides, as I make 
my Soap without Fire, I muft take the Lye that is 
moft concentrated. 
Left the Iron, which is corroded by the Lye, fhould 
enter into the Compofition of the Soap, one need 
only to evaporate the Lyes in earthen Pans put over 
a Balneum Maria? $ but as this Evaporation is (lower, 
it will confume much more Coals. One may even 
fee in thofe Pans by different Marks, that the Liquor 
approaches the deftred Degree of Concentration, 
partly by a Piece of Wood marked with Notches, 
partly becaufe if there is the lead ferruginous Speck 
in the Earth of thofe Pans, the Liquor will penetrate 
that ferruginous Place, and make a Spot there. By 
tiling earthen Pans you will get a very limpid Liquor, 
and which will only have a very pale Straw-colour, 
even after its perfed Concentration. 
The Lye prepared in Iron, being kept for fome 
time, clears up, and leaves a black Sediment, which 
is that Part of the Iron which it has feparated by cor- 
roding the Sides of the Pot. And yet this ferrugi- 
nous Lye, together with the Oil, will form a white 
Soap, if one has let that black Sediment precipitate. 
This Sediment is true Iron: I have made myfelf fure 
of it, by calcining it in a Crucible, after having moid- 
ened it with Oil. 
One Ounce of concentrated Lye to the Degree 
above-mentioned contains Three Drachms Eighteen 
Grains of Salt; when I difi'olve this Salt again in 
diddled 
