SCHNEIDER. 275 



It may be best to summarize all results as follows, in 

 three plainly marked groups: 



Reduct. Oxidat. 



Schneider, 1850, 6 high. 17 high. 



" 1896. 3 high. o high. 



Marchand, 1851, 5 low. 26 high. 



Dumas, 1860, 2 high. 



Persoz, 1864, 4 high. 



Mean, 2 high. 14 high, 



v. Borch, 1851, 33 low. 39 high. 



Roscoe, 1872, 47 low. 45 low. 



Waddell, 1886, 29 high. 



Mean, 16 low. 3 high. 



Pennington and Smith, 1894, 82 high. 



Shinn, 1896, 81 high. 



Mean, 81 high. 



In the first group, we have Ernst Richard Schneider as a 

 masterly analyst, who has proved his Berzelian school in his 

 work on Bi and Sb. Marchand stands equally high. See 

 his work on Hg, S, Ca; he started Scheerer on Mg. Dumas, 

 in the dry way, is a master; see his diamond and calcite 

 work. We conclude that this group is right. For reduc- 

 tion, this mean gives 184.02; for oxidation, 184.15, which is 

 throughout the less reliable. 



Concerning the second group, we have no evidence that 

 Roscoe did the work; probably two chemical students, called 

 "analyst A" and a B " did the work. The other two ana- 

 lysts are not known by any other work of this kind, good or 

 bad. Hence, this group possesses no weight. 



There remains the third group, comprising oxidation 

 work done by or under Prof. Smith. 



We have already stated why we cannot accept his record 

 in this case. The process by weighing the water was decid- 

 edly imperfect in execution the curve of errors running 

 straight up. We have on record bad breaks in reduction to 

 vacuum (see pp. 229-231) and from the formula used (see 

 p. 175) need not wonder thereat. The excessive accuracy in 

 weighing {fancied, and drilled into that institution through 

 Professor Barker) must detract from essentials. 



