64 THE ATOMIC WEIGHTS OF 



of borax has been discussed in detail and rightly or 

 wrongly has been attributed to a transient hydrolysis in 

 the earlier stages of the dehydration. 



(4) The removal of boric acid by the method indicated under 



(1) proved to be complete and left little to be desired. The 

 methyl alcohol used for this purpose was prepared by the 

 saponification of distilled methyl oxalate. The essential 

 factors in the volatilization of boric acid seem to be the 

 following: 



(a) Both the residue treated and the pure methyl alcohol 

 used should be as free from water as possible, if the elimin- 

 ation of the boric acid is to be effected with a minimum of 

 alcohol. 



(6) Frequent evaporations to dryness with small quantities 

 of methyl alcohol, particularly toward the end of the pro- 

 cess, are preferable to fewer evaporations with larger 

 quantities. 



(c) Two or three consecutive evaporations with methyl 



alcohol should, preferably, be followed by solution of the 



residue in water and evaporation to dryness. Toward the 



end of the process these evaporations, with alcohol and 



water, may be alternated to advantage. 



Incidentally, it is safe to assert that, if these precautions be 



observed in the estimation of boric acid in a soluble borate by 



the Gooch-Rosenbladt method, any lack of success is to be 



attributed to the "retainer" used for fixing the boric acid in 



short, to what is taking place in the receiver, not to incomplete 



volatilization of the boric acid. 



(5) The direct conversion of borax into sodium fluoride (i.e., 

 in the presence of hydrofluoric acid) was found to be 

 impracticable and was brought about indirectly through 

 the formate; the latter, after removal of the boric acid, 

 being easily transposed by hydrofluoric acid. The advan- 

 tages of formic acid for this particular purpose have been 

 given. 



(6) The atomic weight of boron was not derived from a series 

 of identical conversions of borax into some fixed salt, but 

 was based on the equivalent quantities of a number of 

 different sodium salts, such as the chloride, sulphate, 



