OF ARTS AND SCIFNCES. 23 



of these have succeeded, the substance being decomposed by solutions 

 of alkalis or acids, in fact even by a solution of carbonic dioxide 

 under pressure, which dissolved both zincic and cobaltous carbonates, 

 and finally left a blackish gray residue. 



Although magnesic hydrate does not dissolve in sodic hydrate under 

 ordinary conditions, we thought that possibly a very strong solution of 

 sodic hydrate might have some solvent action at its boiling point, and, 

 upon trying the experiment, obtained long prismatic crystals, which, 

 however, we found contained only a mere trace of magnesium (0.39 

 per cent), and consisted of the crystallized sodic hydrate recently 

 obtained by Cripps,* as shown by the following analytical results. 



I. 0.5620 grm. of the substance lost 0.2150 grm. of water. 

 II. 0.4115 grm. of the substance gave 0.4585 grm. of sodic sulphate. 



Found. 



II. 



3G.11 



The curious point about this observation, which alone makes it 

 worth recording, is that the solution of sodic hydrate used could not 

 be made to crystallize before it was treated with magnesic oxide, but 

 after such treatment crystallized so rapidly that it was impossible to 

 filter it. The experiment was repeated several times, each time with 

 the same result. What the cause of this diflference in behavior may 

 be we have been unable to determine, but think that possibly a small 

 quantity of sodic carbonate in our solution of sodic hydrate may have 

 prevented the crystallization, which took place as soon as this was 

 converted into hydrate by the magnesic oxide. 



* Pharm. Jour. Trans , Ser. 3, xiv. 833 (1884). 



