OF ARTS AND SCIENCES. 19 



same percentage of zinc, 29.45, but a much larger amount of sodium, 

 19.56, which was undoubtedly due to a small quantity of sodic hydrate 

 left adhering to the crystals, as this was the first preparation we made, 

 and therefore was not pressed out so thoroughly as the later ones, 

 after we had become more familiar with the manipulation. 



Properties of the Fusible Sodic Zincate. 



The substance as precipitated by alcohol from its solution in aqueous 

 sodic hydrate forms a white mass, made up of radiating crystals, often 

 of considerable size. It fuses at about 70°, but, owing to the diffi- 

 culty of drying it, no attempts were made to determine the melting 

 point accurately. Water decomposes it rapidly and completely, con- 

 verting it into a white insoluble powder, which gave on analysis the 

 following result. 



o 



0.1990 grm. of the substance gave 0.1910 grm. of zincic oxide and 

 no sodic sulphate. 



Calculated for Found. 



Zd0 2 H 2 . ZnO. 



Zinc 65.72 80.28 77.03 



The substance therefore seems to be principally zincic oxide mixed 

 with a slight impurity of the hydrate. Alcohol decomposes it in a 

 similar way, but more slowly, as is shown by the following percentages 

 obtained from the analyses of two preparations (IV., V.), which we had 

 attempted to purify by washing with alcohol. 



III. is one of the analyses already given. The substance for this 

 analysis was only pressed with filter paper. IV. was a sample which 

 had been washed three times with common alcohol, while the substance 

 which had the composition given under V. had been washed four times 

 with absolute alcohol. These numbers show that the action of the 

 alcohol consists in gradually removing the sodium as sodic hydrate, 

 and this point is brought out even more sharply by a comparison of 

 the atomic ratios. 



Ziuc : Sodium. 



nr. i. 1.35 



IV. 1. 1.16 



V. 1. 0.89 



