And yet constantly secretly eating its way,
The shrewd acid is making the substance its prey,
  Like some sorrow beyond inquisition,
Which is gnawing the heart and the brain all the while
That the face is illumed by its cheerfullest smile,
  And the wit is in bright ebullition.

But still stealthily feeding, the treacherous stuff
Has corroded and deepen’d some portions enough—­
  The pure sky, and the waters so placid—­
And these tenderer tints to defend from attack,
With some turpentine varnish and sooty lamp-black
  You must stop out the ferreting acid.

But before with the varnishing brush you proceed,
Let the plate with cold water be thoroughly freed
  From the other less innocent liquor—­
After which, on whatever you want to protect,
Put a coat that will act to that very effect,
  Like the black one which hangs on the Vicar.

Then—­the varnish well dried—­urge the biting again,
But how long at its meal the eau forte may remain,
  Time and practice alone can determine: 
But of course not so long that the Mountain, and Mill,
The rude Bridge, and the Figures, whatever you will,
  Are as black as the spots on your ermine.

It is true, none the less, that a dark-looking scrap,
With a sort of Blackheath, and Black Forest, mayhap,
  Is consider’d as rather Rembrandty;
And that very black cattle and very black sheep,
A black dog, and a shepherd as black as a sweep,
  Are the pets of some great Dilettante.

So with certain designers, one needs not to name,
All this life is a dark scene of sorrow and shame,
  From our birth to our final adjourning—­
Yea, this excellent earth and its glories, alack! 
What with ravens, palls, cottons, and devils, as black
  As a Warehouse for Family Mourning!

But before your own picture arrives at that pitch,
While the lights are still light, and the shadows, though rich,
  More transparent than ebony shutters,
Never minding what Black-Arted critics may say,
Stop the biting, and pour the green fluid away,
  As you please, into bottles or gutters.

Then removing the ground and the wax at a heat,
Cleanse the surface with oil, spermaceti or sweet,
  For your hand a performance scarce proper—­
So some careful professional person secure—­
For the Laundress will not be a safe amateur—­
  To assist you in cleaning the copper.

And, in truth, ’tis a rather unpleasantish job,
To be done on a hot German stove, or a hob—­
  Though as sure of an instant forgetting,
When—­as after the dark clearing-off of a storm—­
The fair Landscape shines out in a lustre as warm
  As the glow of the sun, in its setting!

Thus your Etching complete, it remains but to hint,
That with certain assistance from paper and print,
  Which the proper Mechanic will settle,
You may charm all your Friends—­without any sad tale
Of such perils and ills as beset Lady Sale—­
  With a fine India Proof of your Metal.