1. Highly milled parboiled rice was found to be rich in the antineuritic vitamin B1, while roughly milled raw rice was deficient. In estimating the content of vitamin B1 the method of Chick and Roscoe was used.

2. Exact comparison was made of the vitamin B1 potency of two samples of rice, the one raw, the other parboiled, after similar degrees of milling. The vitamin value of the unmilled samples was equal, but when each was highly milled to an equal degree, as judged by weight of polishings removed in a hand rice mill, the parboiled sample retained the vitamin while the raw sample did not.

3. Polishings from parboiled rice were found to contain less vitamin B1 than those from raw rice.

4. Parboiled rice contains more P2O5 than raw rice milled to the same degree.

5. It is probable that when rice is steamed in the process of parboiling, the vitamin B1 and some of the phosphate contained in the germ and pericarp diffuse through the endosperm.

6. The P2O5 content of raw rice is a good index of vitamin B1 value, but in parboiled rice a low percentage of phosphate is compatible with the presence of the vitamin.

Thanks are due to Miss L. M. B. Patterson who kindly made the phosphate estimations recorded in the paper. I am indebted to the Director of Agriculture, British Guiana, for a number of rice samples. The rice mill used was kindly lent by Jackson and Son, 30, Mincing Lane, E.C. 3. I am grateful to Miss Chick for her continued interest in these experiments.