Sodium metabisulphite appears to be an effective preservative for grass, giving a fresh‐coloured, pleasant‐smelling material of higher pH than normal silage. The metabisulphite acts as a bacteriostatic agent, permitting little bacterial fermentation; very considerable proteolysis and hydrolysis of carbohydrate takes place without the losses of resultant units normally associated with bacterial fermentation. The hydrolysed protein appears almost quantitatively as amino‐acid and peptide with little ammonia formation, and the carbohydrates, including some from cell‐wall polysaccharides, accumulate as reducing sugars; the final concentration of these may be greater than the total water‐soluble sugar of the fresh grass. Similarly, there is a marked sparing action on the malic and citric acids. Changes in these components have been followed in some detail in grass ensiled with and without addition of metabisulphite. It is pointed out that consistent results will depend on intimate mixing of grass and reagent.

The more abundant of the non-nitrogenous non-volatile organic acids in extracts of perennial rye-grass are quinic, malic and citric. Succinic acid and others are present in small amount. An investigation of changes taking place during ensilage and other conservation processes is described, lactic acid and the volatile fatty acids being determined simultaneously. In silage there is rapid and complete disappearance of malic and citric acid ; this is also noted to a lesser extent during wilting and drying whereas, in grass preserved with metabisnlphite, there is loss of malic acid alone.