276 balahd's researches concerning the nature of 



The salts of lead possess no advantage over those of mercur)'. If a 

 solution of acetate or nitrate of lead be poured into a decolorizing 

 chloride, a precipitate of chloride of lead is immediately formed ; but 

 this chloride is itself susceptible of being altered by the chlorite. If it 

 is not soon separated from the liquor, it becomes quickly brown, is 

 converted into peroxide, and gives out a strong smell of chlorine. This 

 double phsenomenon is undoubtedly effected by the decomposition of 

 tlie chlorous acid. 



Since the salts of lead did not, any more than those of mercury, lead 

 to the end intended, I was compelled to have recourse to the action of 

 those of silver ; they are more costly, it is true, but they apparently 

 would be followed with more success. My attempt was not altogether 

 unsuccessful. Nevertheless tlie employment of the salts of silver is 

 attended with some inconveniences which it is requisite to state. 



If a neutral solution of nitrate of silver be precipitated by a solution of 

 chloride of lime, containing a slight excess of lime, a great quantity of 

 chloride of silver is precipitated, and there is formed at the same time 

 oxide of silver, which imparts a grey colour to the deposit obtained. 

 The supernatant liquid is strongly decolorizing; but if an attempt be 

 made to separate it by filtration, a brisk effervescence is produced as 

 soon as a little has filtered, and when tlie filtration is over the liquor has 

 completely lost its decolorizing property. The gas which is evolved in 

 this case is oxygen. Berzelius had previously observed the phsenome- 

 non which I have now mentioned, and discovered the cause of it. I 

 have ascertained in operating directly with the chlorites and the oxide 

 of silver, that these salts occasioned the formation of chloride of silver 

 and a disengagement of oxygen. This oxygen is produced, both from 

 the chlorous acid and the decomposed oxide. A portion of this oxygen 

 gas evolved is absorbed by the portion of oxide in excess in the liquor, 

 and converts it into peroxide, whilst the remainder is given out in the 

 state of gas. In trying to obtain free chlorites, the precipitation of oxide 

 of silver must be avoided, and the decolorizing chlorides must have no 

 excess of alkali, which is avoided by neutralizing them with nitric 

 acid; but it is requisite not to add excess of it, which would be as 

 active, though a different cause of the decomposition of the chlorite. 



If, indeed, a solution of chloride of lime supersaturated with nitric 

 acid be precipitated by nitrate of silver, the mass of chloride of 

 silver formed is soon raised by abundant bubbles of chlorine ga.s, and 

 the decolorizing property is in a great degree lost. If an attemjit be 

 made quickly to remove the chloride of silver, which is the cause of 

 this decomposition, from the sujiernatant liquid, by throwing it in a 

 cloth and pressing it strongly, the reaction is accompanied with a 

 disengagement of a very considerable degree of heat. Some direct expe- 

 riments, which I shall state hereafter, have proved that the chlorous 



