614 



PROFESSOR DITTMAR AND MR JOHN M'ARTHUR ON 



Page. 



Set. 



604 



I. 



605 



II. 



606 



III. 



606 



IV. 



607 



V. 



Per cents, of 

 KC1 in Salt. 



A : p. 



(y : A) K 2 C1 S . 



{p : A )K 2 Cl 2 =195-73 (Set I.). ' 



95 



(•76270) 



195-60 



Mean (p : A ) K 2 C1 2 may 



95 



(•76087) 



196-06 



perhaps be put down at 



95 



•76116 



195-99 



195-98 + 013=19611. 



82 



•76157 



195-89 





33-3 



•75980 



196-34 





eans, 



•76084 



195-98 





ilated from II] 



:., iv., & v. 



All. 





Set I. Salts made into normal sulphates; platinum used = 1*075 times 

 the calculated minimum. 



Set II. A combination of Tatlock's and Finkener's methods. 



Set III. Only sulphuric acid added ; no evaporation : platinum used, =1*25 

 times the calculated minimum. 



Only sets III., IV., and V. correspond to our present method : hence the 

 mean factor A : p was calculated from only these 3 sets. 



We have recalculated the 12 analyses of sets III., IV., and V., with the new 

 factor 076084, and found the " errors " of the recalculated numbers. 



Set, 



III. 



0-75 



A, about 



Analysis, (1) (2) (3) (4) 



Error, --07 --82 +11 --50 





IV. 

 0-65 







(1) 



+ •20 



(2) 



-219 



(3) 



-•33 



(4) 



-17 



V. 



0-266 gm. 



(1) (2) (3) (4) 



+ •34 +-23 +18 +-70mg. 



Mean error = =b 0*49 mg., or, excluding No. 2 in IV., it is ± 33. 



B. Tatlock's. 



In the following table, the first column refers to the respective page of 

 this memoir ; the third gives the percentage of KC1 in the set of salts analysed ; 

 the figures in the second are reference marks. 



Page. 



612 (1) 



612 (2) 



613 (3) 

 613 (4) 



Per cent, of 

 KC1 in Salt. 



95 

 95 



82 

 33-3 



A :C. 



A :C. 



(C : A )K 2 C1 2 . 



A :p. 



(p : A )K 2 Cl a 



■30673 * 



•30563 



48811 



•76011 



196-26 



•30602 



•30463 



489-71 



•76019 



196-24 



•30630 



•30489 



489-29 



•76018 



196-24 



•30648 



(-30324) 



491-96 



(-75692) 



(197-09) 



•30627 



•30505 



489-04 



•76016 



196-25 



Means, . 

 Calculated from (2), (3), & (4) (1),(2),&(3) (1),(2),&(3) (1),(2),&(3) (1),(2),&(3) 



Recalculating the 12 analyses we made (by Tatlock's exact method) 

 with the factor 0*30627, we arrive at the following errors for the individual 

 results : — 



From the one anatysis of this set in which Tatlock's directions were strictly obeyed. 



