Manufacturers have mainly depended upon imported clays, but the Western glass-makers have used Missouri clay with success. In the east it has not yet come into general use. Of the imported, that from Stowbridge is considered best. Garnkerk is a strong clay, and, if well selected, will rival any other. The analyses are for
STOWBRIDGE,
| Silica, | 64 | parts, |
| Alumina, | 20 | " |
| Lime, | 1 | " |
| Iron, | 3 | " |
GERMAN,
| Silica, | 46 | parts, |
| Alumina, | 34 | " |
| Iron, | 3 | " |
GARNKERK,
| Silica, | 53 | parts, |
| Alumina, | 43 | " |
| Lime, | 1 | " |
| Iron, | 1 | " |
FRENCH,
| Silica, | 40 | parts, |
| Alumina, | 31 | " |
| Iron, | 3 | " |
WESTERN,