Examination of the contents of the three types of silo in use at the Iowa Agricultural Experiment Station showed the following chemical changes during the actual period of silage formation.

1. Non-reducing sugar was rapidly changed to reducing sugar , and the latter then decreased in amount but did not disappear completely.

2. The amount of volatile acids increased daily.

3. In the concrete silo, as already demonstrated for the hollow tile and wooden stave silos, the racemic lactic acid produced showed a daily increase.

4. Alcohol was formed in small amounts in each silo.

5. Carbon dioxide developed very rapidly after filling the silo.

6. Free oxygen disappeared entirely after the second or third day.

7. The maximum temperature observed in any of the three silos was 91 0 Fahrenheit.

8. Within the limits of this investigation, no differences were noted which might be attributed to difference in the material of which the silos were constructed.