French Prize Memoirs, 73 



and decomposed the other hy sulphuric acid : I obtained the 

 chloric acid, with which I made many combinations, the proper- 

 ties of M'hich I intend to describe on a future occasion. 



" I evaporated and crystallized the portion of chlorate of ba- 

 rytcs which I had kept in reserve. This being done, I dried a 

 certain ])ortion of it in order to inspect the water of crybtalliza- 

 tion. I put two grammes of the latter into a platina crucible, 

 which I exposed to the fire in order to determine the loss which 

 this salt should undergo on being decomposed, which would have 

 given me the quantity of oxygen, at least in an approximative 

 manner, for I already knew the barytes. But shortly after this 

 salt was exposed to the fire, a detonation took place which re- 

 sembled a musket-shot at least. The furnace was broken ; the 

 platina crucible, although very thick, was rent in several places ; 

 the bottom, which was flat, was driven in like a cone ; and the lid 

 was forced against the chimney, to which it stuck, assuming the 

 same form. 



" Although the circumstance astonished me at first, yet when 

 I reflected on the way in which chlorate of barytes thus prepared 

 acts on burning coals, my surprise was lessened. In fact, it does 

 not fuse like the chlorate of potash ; it detonates rapidly and with 

 great noise, even upon the ])arts of the charcoal where no more 

 sign of combustion is observed. 



" When reflecting on the cause of this detonation, it occurred to 

 me at first that it consisted in a rapid disengagement of oxygen ; 

 but chlorate of potash, prepared directly with my chloric acid, 

 having presented the same phenomenon, whilst that prepared hy 

 the common process does not present it, we must seek for it 

 elsewhere ; and I soon found that it was to the acetate of barytes 

 that it ought to have been attributed. 



" We niust therefore admit that the acetic acid employed to 

 rxpedite the operation does not confine itself to dissolving the 

 phiijphate of silver, as generally supposed : it also decomposes 

 a part of the chlorate of barytes, from which it should seem that 

 it drives oif the acid or decomposes it. 



" From what, I have said, it appears that the acetic acid ought 

 not to i)e employed for preparing the chloric acid ; for, indepen- 

 dent of the troublesome accidents which might result, the acid 

 obtained is not fine, any more than the combinations made with it. 



" The process of Mr. Chenevix being very tedious v^lien vin- 

 egar is not employed, I am endeavouring to find one more expe- 

 ditious, and I expect to succeed." 



The French Class of Physical and Mathematical Sciences has 

 proposed the following as the subject of a prize memoii ; mz. To 

 determine, 1st. The march of the mercury thermometer, at least 



from 



