T h e sulphate and nitrogen contents of cellulose nitrates prepared from mixed acids containing different amounts of sulphuric acid were compared. The sulphate content showed a tendency to decrease with increasing nitrogen, for instance it was 1.9G% for 10.54% and 0.44% for 13.31%. Similar results were obtained with a series of wood cellulose nitrates, for instance 2.40% for 11.01% and 0.01% for 12.47%. With pracLically the same amount of sulphuric acid in the mixed acid, cellulose nitrates were prepared and the sulphate and nitrogen contents were compared. For unstabilized cotton cellulose nitrates, the sulphate content decreased steadily with increasing nitrogen content. Similar results were obtained with wood cellulose nitrates.