18 PROCEEDINGS OP THE AMERICAN ACADEMY 



Each of these three analyses was made with a sample from an en- 

 tirely separate preparation, in order to determine whether the substance 

 had a definite composition, and when it is remembered that it could 

 not be purified by crystallization, and was dried only imperfectly by 

 pressing with filter paper, the agreement is as close as could be ex- 

 pected ; but it is obvious that in a case like this the atomic ratios are 

 of much more importance than the percentages, and we have accord- 

 ingly calculated them as follows. 



Atomic Ratio of Zinc to Sodium in Fusible Sodic Zincate. 



Zinc 



I. 1. 



II. 1. 



III. 1. 



Sodium. 



1.36 

 1.35 

 1.35 



The agreement between these numbers proves conclusively that the 

 substance is a definite compound, and that the proportion of zinc to 

 sodium is as three to four. In trying to calculate a formula for it, we 

 have felt much doubt in regard to the amount of water of crystalliza- 

 tion for the reasons given above ; but the one finally adopted by us 

 gives percentages which agree so well with those found, that it cannot 

 be far from the truth, especially as the amounts of water found are 

 about as much higher than those calculated as was to be expected. 

 The constitutional water, on the other hand, comes very high, but we 

 do not have much faith in this determination. 



Calculated for 

 ZusOeNa^H, 17 HjO. 



Zinc 28.28 



Sodium 13.80 



Water 44.24 



Constitutional Water 2.60 



To prove that the substance contained water, and not alcohol of 

 crystallization, a combustion of it was made in the usual manner, but 

 only a mere trace of carbonic dioxide was obtained. 



The formula of this substance, ZugOgNa^Hj . 17 HoO, agrees, except 

 in water of crystallization, with that of the substance analyzed by 

 Malaguti (see page 15), which, written in the same way, becomes 

 Zn,.0,.(NHJ^H2 . 9 H2O. This, as has been mentioned already, is the 

 only zincate of which an analysis has been published. 



We have made only one analysis of another preparation of this sub- 

 stance, which is comparable to those given above ; this gave about the 



