| US Patent: 255,725 
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| Hardening metals | 
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| Patentee: |  |
 | Charles M. Daboll (exact or similar names) - New London, CT |  
 
 
 
 
| Manufacturer: |  | Not known to have been produced |  
 
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| Patent Dates: |  
| Applied: | Aug. 25, 1881 |  
| Granted: | Mar. 28, 1882 |  USPTO (New site tip)
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                        Jeff Joslin
 Vintage Machinery entry for Wilson Mfg. Co. (CT)
 
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| Description: |  | The inventor is known to have worked for I. Wilson of New London, which became Wilson Mfg. Co.This patent is a companion to patent 255,724 for a roller-bearing pulley for use on ships. This patent provides a recipe for hardening the cast iron components: a bath of 40 gallons water, 50 lb salt, 2 lb saltpeter, 5 lbs potassium cyanide, 5 lb sulphuric acid. The parts are heated first but no hints are provided as to how hot. |  |