Sorry CG, I've one (don't think mines an ink bottle) with a 'C' in a triangle and the number 3. Never really researched old bottles...maybe time I start.
Could be a Carter Bros. Ink, in 1865 William's cousin, John W. Carter, joined the enterprise and the name became "Carter Bros. & Company." John W. Carter focused his efforts on the ink part of the business which, along with the sales efforts of James P. Dinsmore, resulted in such growth that the ink business was separated from the paper business and moved into its own quarters in 1868."