#Q M. CHIKASHIGE. 



the perchloric acid. The calculation is for Hg(Cl0 4 ),,6H 2 0. 



Behaviour of mercuric perchlorate when heated. — Mercuric perchlorate, 

 as dry as possihle, melts at about 34°, in dry air. Heated in a long 

 narrow tube, closed only at its lower end, the salt melts to a colourless 

 liquid, which boils freely, without noticeable change, even in a bath 

 of boiling sulphur. In reality, it is decomposed, and at temperatures 

 far below this, but since the products of its decomposition, which boil 

 off, condense and flow down again, the salt is recovered when the tube 

 is cooled. 



Even at the common temperature, as already mentioned, mercuric 

 perchlorate very slowly decomposes in dry air, but, in a current of 

 dried air at 120°, the evolution of water and perchloric acid becomes 

 manifest in the shape of white fumes. By raising the temperature 

 gradually and maintaining it then at 150° until the weight of the 

 residue becomes constant, there is obtained a homogeneous and ap- 

 parently definite compound. 



Oxymercuric perchlorate, this compound, is white and amorphous; 

 it is unchanged by the heat of boiling mercury, and only slowly 

 affected by that of boiling sulphur. Heated to a point a little below 

 that at which mercuric oxide freely decomposes, it is completely 

 changed into oxygen and chlorine gases, sublimates of mercuric and 

 mercurous chlorides, and a residue of mercuric oxide. By water it is 

 decomposed into mercuric perchlorate and mercuric oxide, besides 

 insignificant quantities only of chloride and chlorate. In a quantita- 

 tive experiment, it was found to yield to water, mercury 12'()4, and 

 perchlorate radical 12'90 per cent, of the weight of the salt which had 



