As a preliminary to a study of certain regions of the four-component system Na20-Si02-Al20g-H20 at 25°C. some confirmatory work on the three-component systems Na20-Al20g-H20 and Naü0-Si02-H20 seemed advisable. The system Na20-Al20g-H20 has been investigated by Goudriaan (3) and by Fricke and Jucaitis (2) at 30°C. The present work on this system was carried only to the point necessary to confirm the results of the latter investigators, allowing for the 5°difference in temperature.The system Na20-Si02-H20 has been investigated by Harman (4). The results presented at this time differ in several important respects from those reported by that investigator. MATERIALS Three materials were used for the preparation of the solutions: AlüOg'3 H20, Na20-Si02-9 H20, and a solution (ca. 50 per cent) of sodium hydroxide.The alumina trihydrate was prepared by slow hydrolysis of c.p. sodium alumínate solutions, filtered off, rapidly washed with cold water on a suction filter, and dried in a steam chest. One such preparation gave 35.3 per cent loss on ignition (theoretical, 34.65 per cent H20) and contained less than 0.2 per cent sodium oxide.The hydrated sodium metasilicate was prepared by water recrystallization of the c.p. salt, was filtered with exclusion of carbon dioxide under a ' This article is part of a thesis presented by J. W. Sprauer to the Graduate School of Purdue University in partial fulfillment of the requirements for the degree of Master of Science.

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