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49. What compositions are made use of for preserving iron cannon?
| 1. | Black lead, pulverized, | 12 |
| Red lead, | 12 | |
| Litharge, | 5 | |
| Lampblack, | 5 | |
| Linseed Oil, | 66 | |
| Boil it gently about twenty minutes, | ||
| during which time it must be | ||
| constantly stirred. | ||
| 2. | Umber, ground, | 3.75 |
| Gum Shellac, pulverized, | 3.75 | |
| Ivory black, | 3.75 | |
| Litharge, | 3.75 | |
| Linseed Oil, | 78 | |
| Spirits of turpentine. | 7.25 | |
| The oil must be first boiled half an hour; | ||
| the mixture is then boiled 24 hours, | ||
| poured off from the sediment, and | ||
| put in jugs, corked. | ||
| 3. | Coal tar (of good quality), | 2 gals. |
| Spirits of turpentine, | 1 pint. |
In applying lacker, the surface of the iron must be first cleaned with a scraper and a wire brush, if necessary, and the lacker applied hot, in two thin coats, with a paint brush. It is better to do it in summer. Old lacker should be removed with a scraper, or by scouring, and not by heating the guns or balls, by which the metal is injured.
About 5 gallons of lacker are required for 100 field guns and 1000 shot; about 1 quart for a sea-coast gun. Before the lacker is applied, every particle of rust is removed from the gun, and the vent cleared out.
50. How many gallons does a cubic foot contain?
7.48 gallons.
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