Having now regard to the production of a solution of maximum concentration of dissolved solids, the following conditions were asertained to fulfil the requirement, and, in fact, may be regarded as the economic optimum:
| Proportion of total liquid | 6 times wt. of cellulose |
| Concentration of acid | 0.5 p.ct. H2SO4 |
| Pressure | 10 atm. |
| Duration of digestion | 1.5 hour |
giving a yield of 41 p.ct. 'reducing sugar' calculated to the original cellulose (dry).
Alcoholic Fermentation of Neutralised Extract.—The liquors were found to ferment freely, and on distillation to yield a quantity of alcohol equal to 70 p.ct. of the theoretical—i.e. on the basis of the numbers for copper oxide reduction.
(b) Hydrolytic 'Conversion' of Wood (Lignocellulose).—A similarly systematic investigation carried out upon pine sawdust established the following as optimum conditions:
| Proportion of total liquid | 5 times wt. of wood |
| Concentration of acid | 0.5 p.ct. H2SO4 |
| Pressure | 9 atm. |
| Duration of digestion | 15 minutes |
giving a yield of 20 p.ct. 'reducing sugar,' calculated from the 'Fehling' test.
Fermentation of the neutralised extracts gave variable results. The highest yields obtained were 60 p.ct. of theoretical, the author finally concluding that under properly controlled conditions of inversion and fermentation 100 kg. wood yield 6.5 l. absolute alcohol.