The difficulty one meets in obtaining a supply of melibiose is doubtless the explanation of the fact that this rare disaccharide is rather seldom the subject of scientific investigation. There are two reasons why the sugar is so rare: first, the only known source for it is the trisaccharide raffinose, which itself has been somewhat rare, and, second, the methods which may be found in the literature for preparing melibiose from raffinose are not satisfactory as regards the yield, in part because

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... the details of procedure are not specified with the exactness that is necessary to enable a reader to repeat an author's preparation of a substance which crystallizes with much difficulty. Being in need recently of a supply.of melibiose, we worked out the details of its preparation from raffinose, and the procedure which we recommend, after the preparation by it without difliculty of nearly a kilogram of melibiose, will presently be described. The Source.-As mentioned, rafEinose is the only known natural source for melibiose. Recently we have described in detail an inexpensive method for the preparation of raffinose from cottonseed meal' which yields about 4% of the weight of the meal as pure crystalline raffinose. This quantity is approximately half the raffinose that exists in the meal. Raffinose can now be prepared with certainty and a t little expense and