SCIENTIFIC CONGRESS OF CARLSRUHE. 363 



properties in presence of a base, and vice versa, so likewise does ozone 

 affected with the sign -|- for instance, lose its oxydizing properties in 

 presence of ozone affected with the sign — . 



This polarity of the different states of chemical activity in which 

 oxygen may present itself, results still more from the manner in which 

 certain oxyds act in regard to chlorhydric acid. In this case the per- 

 oxyde of manganese is replaced by a protochloride, chlorine, and 

 water. 



Mn O 2 + 2 CI H — CI Mn + CI + 2 HO (1.) 



With the peroxide of barium, on the contrary, we obtain not chlorine, 

 but oxygenized water. 



Ba O 2 + CI H = CI Ba + HO 2 (2.) 



To the group of the peroxyde of manganese are referable the per- 

 oxides of lead, silver, nickel, cobalt, bismuth, and vanadium; to that 

 of the peroxide of barium pertain the peroxides of calcium, strontium, 

 &c. 



M. Schoenbein calls the former ozonides, the latter antozonides. 



The ozonides do not give oxygenized water ; in presence with it, they 

 occasion a disengagement of common oxygen, and are decomposed in 

 decomposing the oxygenized water . They color the tincture of guaiacum, 

 blue. 



The antozonides do not decompose oxygenized water; and do not 

 give the blue tint to the tincture of guaiacum. On the contrary, they 

 discharge this blue tint when it has been communicated by an ozonide. 



In fine, the views here given, which assign to the ozonides a polarity 

 distinct from that of the antozonides may be considered as being estab- 

 lished by the fact that the former are, beyond question, electro-negative 

 in reference to the latter. 



One of the great international questions which is of constant recur- 

 rence, and which calls for a solution, attaches itself to the subject of 

 weights and measures, the difference of which in different countries 

 occasions no little embarrassment to commerce and to travelers. 

 Several States have already adopted the metrical system; others 

 would do the same if this system had been invented elsewhere than in 

 France. Now, while such States lag behind through an inexcusable 

 and short-sighted prejudice, science, which is of no country, has long 

 since exchanged the pound, the ounce, the dram, the inch, the foot, the 

 ell, for the gramme and its derivatives, the metre and its multiples or 

 submultiples ; so that it' is very rare to find a grave scientific treatise, 

 English or German, which has not substituted the metrical system for 

 those irregular weights and measures. 



This species of scientific revolution took place in Germany towards 

 the year 1830; and in bringing it about, none was more influential 

 than the man who has so largely contributed to shape the scientific 

 destinies of his age, M. Liebig, with whom we may associate^ M. 

 Woehler: by introducing, after the example of the French chemists, 

 the metrical system into their laboratories, their publications, and 

 consequently into the Annalen der Chemieund Pharmacie, their recog- 

 nized organ, they have naturally imposed the use of that system on their 



