At this date the lustra-celluloses known may be divided into four classes.
1. 'Artificial silks' obtained from the nitrocelluloses.
2. 'Lustra-cellulose' made from the solution of cellulose in cuprammonium.
3. 'Lustra-cellulose' prepared from the solution of cellulose in chloride of zinc.
4. 'Viscose silks,' by the decomposition of sulphocarbonate of cellulose (Cross and Bevan).
Group 1. The early history of the Chardonnet process is discussed and some incidental causes of the earlier failures are dealt with. The process having been described in detail in so many publications the reader is referred to these for details. [See Bibliography, (1) and (2), (3) and (4).] The denitrating treatment was introduced in the period 1888-90 and of course altogether changed the prospects of the industry; not only does it remove the high inflammability, but adds considerably to softness, lustre, and general textile quality. In Table I will be found some important constants for the nitrocellulose fibre; also the fibre after denitration and the comparative constants for natural silk.
Table 1.
| Tenacity | Elasticity | |
| (grammes) | (% elongation) | |
| Nitrocellulose according to Chardonnet German Patent No. 81,599 | 150 | 23 |
| The same after denitration | 110 | 8 |
| Denitrated fibre moistened with water | 25 | — |
| Nitrocellulose: Bronnert's German Patent No. 93,009 | 125 | 28 |
| The same after denitration (dry) | 115 | 13 |
| The same after denitration (wetted) | 32 | — |
| Natural silk | 300 | 18 |
1. Tenacity is the weight in grammes required to break the thread.
2. Elasticity is the elongation per cent. at breaking.