410 On the Preparation of Amber Varnish , 
In boiling the varnish, care must be taken that it may 
not boil over or catch tire. Should this happen to be the 
case, it must not be extinguished by water ; for this mode 
would occasion such a sputtering, that the operator would 
be in danger of having his face bespattered with the boih 
ing varnish. The best method, therefore, is to cover the 
vessel in such a manner as to exclude the air, and with 
any thing that may be at hand, such as a piece of wood, 
plate of iron, or any thing else that may cover the vessel 
and extinguish the flame. 
1. Iron Stain . 
Eight ounces of iron-filings and thirty-two ounces of 
common aquafortis. The aquafortis must first be mixed 
with sixteen ounces of water in a stone jar, and then a 
few of the filings are to be added, and well stirred round 
with an iron or wooden spatula. This preparation must 
be made in a chimney, because the solution is attended 
with heat, effervescence, and the disengagement of noxious 
vapours : it is of importance, also, that the jar should be 
of such a size as to prevent the matter from running over. 
After the greater part of the iron has been dissolved in 
this manner, the solution will be of a yellowish brown 
colour. As soon as the mixture has cooled, pour it into 
a bottle placed in a pan, and let it stand a day or two, 
without being corked, over a warm stove ; during which 
time shake the bottle frequently. The bottle being then 
suffered to cool, pour into it one pound three quarters of 
river water, stirring it well round, and leave it at rest for 
a few minutes till the undissolved part sinks to the bot- 
tom : then pour the solution into another bottle, and cork 
it up for use. 
When this preparation has been carefully made ac- 
cording to the above directions, you obtain a yellowish 
brown solution, which may be employed for staining. In 
