US 220394

Patent Overview — US 220394

Title: Improvement in Processes for Preparing Paint from Coke
Inventor: Henry Lempfert, of Green Point, New York
Patent number as printed in the specification: No. 220,391 (the source page lists the publication number as US220394A)
Publication date: October 7, 1879
Application filed: February 12, 1879
Assignee: None identified in the supplied text
Source: https://patents.google.com/patent/US220394/en

Purpose and plain-language scope. The patent describes a three-step way to make a paint pigment from coke:

1. Wet grinding — Reduce coke "of any kind" to a fine powder by the action of a suitable mill in the presence of water.
2. Reheating (calcining) — Introduce the wet mass from the mill into a kiln and heat it to a red heat, "so as to drive out the moisture and to burn all impurities still mixed with the coke, particularly sulphur."
3. Combining with oil — After reheating, grind the coke together with linseed oil, "ready to be used as a paint."

The patent states the resulting paint "can be mixed with any suitable vehicle," and is "of particular advantage for painting ship-bottoms," though it "may be used for various kinds of work."

What is claimed. A single claim covers the described process: reducing coke to powder in the presence of water, reheating the wet mass to expel moisture and destroy remaining impurities, and finally grinding the coke with linseed oil, "substantially in the manner set forth."

Express disclaimer. The inventor expressly does not claim the manufacture of a paint pigment by grinding coke, coal, charcoal, etc. in a dry state, then mixing with water or spirit and grinding in a thick pasty state, reheating the wet mass, and finally mixing with oil or varnish with the water or spirit driven off — stating "such is not my invention."

What the excerpt does not establish. The supplied text does not identify an assignee, any ownership transfer, or litigation. It also does not establish validity, the actual prior art beyond documents listed under "Similar Documents," or whether the patent-number discrepancy (220394 vs. 220,391) reflects a transcription error in the source or the original printing. No ranges of temperature, time, or proportions are given beyond "a red heat." The testimony signature block names "E. F. KASTENHUBER," whose role is not explained in the excerpt.