The Frock Suit

Frock CoatThe frock coat was single or double breasted, usually black, bottom hem above the knee, and distinguished by a squared shape at the bottom front. Its companion, the morning coat was single breasted and has a rounded, swallow tail shape. Both were referred to as "morning" dress, to distinguish them from evening dress. Both were worn with top hats. In the South and West however, top hats were often replaced by broad brimmed, low crowned hats for everyday frock suit wear. Garish colorful vests, often of patterned Chinese silk, were still common with frock suits through the early '60s, but were replaced by black, white or gray by the '70s. The same applied to ties. Colorful cravats were often seen with Frocks in the '60s, but by the '70s most, but not all, had been replaced by small black bow ties.
Frock Coat
In the 1850s and 60s, it was common for those wearing black frock coats to wear black trousers. from the '60s on, it became more fashionable to wear charcoal gray trousers, often pin striped.

"The morning dress for gentlemen is a black frock coat, or a black cut-away, white or black vest, according to the season, gray or colored pants, plaid or stripes according to the fashion, a high silk stove pipe hat, and a black scarf or necktie. A black frock coat with black pants is not considered a good combination.. The morning dress is suitable for garden parties, Sundays, social teas, informal calls, morning calls and receptions."
"Our Deportment" 1879

"At afternoon funerals, wear a frock coat and top hat. Should the funeral be your own, the hat may be dispensed with."
The Cynic's Rules of Conduct. 1905

Key elements of a Frock Suit (Click on the image for a larger view):

* Small black bow tie. Colorful ties are seldom seen with frock suits after the 1860s.
* Black wool vest (it might well have been colorful silk in the 1860s) This one is double breasted, but it could just as easily have been single breasted.
* Watch chain. This one is made of braided hair.
* Shirt cuffs visible at the wrist.
* Winged shirt collar on a white shirt. Something similar can be purchased at any modern tux shop. Note that a colorful shirt is never worn with a frock suit. It is always white.