16 PROCEEDINGS OP THE AMERICAN ACADEMY 



The principal results which we have obtained can be briefly sum- 

 marized as follows. From a solution of zincic oxide in aqueous 

 sodic hydrate two crystalline sodic zincates can be separated by the 

 action of alcohol; the principal product, which fuses below 100°, has 

 the formula ZngOgNa^Hg . 17 HgO, the other, which does not fuse at 

 300°, is (Zn02NaH)2 . 7 HgO. Both substances are decomposed into 

 zincic oxide and sodic hydrate by water or alcohol. We had hoped 

 at first to extend our work to other zincates, but, after a number ot 

 experiments, have abandoned this intention, as with potassic hydrate 

 no crystalline or definite compound could be obtained, and, although 

 ammonic hydrate gave a product crystallizing in needles, it was ob- 

 tained with difficulty, and proved to be of varying composition. We 

 give, however, at the end of this paper, a brief account of the negative 

 results of these experiments, and of some others in similar directions. 



Preparation of the Sodic Zincates. 



The sodic zincates can be prepared by the action of sodic hydrate 

 on either metallic zinc, zincic oxide, or zincic hydrate, and the product 

 seemed to be the same in every case. It is most convenient, therefore, 

 to prepare them from zincic oxide, as the metallic zinc dissolves very 

 slowly, long boiling with aqueous sodic hydrate being necessary to pre- 

 pare a sufficiently strong solution. On the other hand, we have not 

 succeeded in preparing the sodic zincates from sodic carbonate, as a 

 mixture of this substance with zincic oxide showed no loss of weight 

 even when kept at a white heat for some time. The method adopted 

 by us consisted in dissolving zincic oxide in a strong aqueous solution 

 of sodic hydrate,* with the aid of heat, in a flask, which was usually 

 closed with a cork fitted with a set of potash bulbs, to prevent the 

 absorption of carbonic dioxide by the alkaline liquid, but this precau- 

 tion was not absolutely necessary. The solution, after it had cooled, 

 was treated with twice or three times its volume of alcohol, and the 

 mixture, after being thoroughly shaken, allowed to stand securely 

 corked for about twenty-four hours. During this standing two layers 

 were formed, a heavy aqueous solution, and a lighter alcoholic liquid. 

 These were separated, the aqueous solution treated again with alcohol 

 in the same way, and this extraction with alcohol repeated until the 

 heavier portion solidified shortly after it had been removed from the 

 alcohol, which happened usually after the third or fourth extraction. 

 The crystalline mass thus obtained we have called fusible sodic zinc- 



* The sodic hydrate used by us had been purified by alcohol. 



