2 minutes, shallow or watery; shadows, yellowish; drapery, brown.

2 1/4 minutes, soft; face, scarcely white; shadows, neutral; drapery, fine
dark brown linen somewhat blue.

2 1/2 minutes, clear and pearly; shadows, clear and positive,
of a purple tint; drapery, jet black, with the dark shades
slightly frosted with mercury.

2 3/4 to 3 minutes, hard and chalky; shadows, harsh; drapery, roughened,
and misty with excess of mercury.

The foregoing results will be found general.

There are numerous opinions among our operators in regard to the quantity
of mercury necessary for a bath. As regards this, I need only say,
similar results occur when two pounds or two ounces are used,
but the quantity generally employed is about a quarter of a pound.
I am of the opinion that one ounce will answer as well as a larger quantity.
I know of no better proof in favor of a small quantity than that
presented in the following incident. Several years since, an operator
(Mr. Senter, of Auburn, N.Y.) of my acquaintance, was requested to go
several miles to take a Daguerreotype portrait of a deceased person.
He packed up his apparatus and proceeded over a rough road for some
distance to the house where he was to take the portrait, and arranging
his apparatus, with all the expedition which the occasion required,
after having everything in usual order (as was supposed),
he proceeded and took some ten or twelve very superior impressions.
They were fine, clear, and well developed. After taking the number ordered,
he proceeded to repack his apparatus, and to his surprise, when he took