1G8 PROCEEDINGS OF THE AMERICAN ACADEMY 



present, is still in condition to give annoyance, and the other bases are 

 yet to be seiiarated. 



Advantage has long been taken of the volatility of free boric acid 

 with hydrofluoric acid or with alcohol to secure its removal from fixed 

 substances, but so far as I know no attempt has been made heretofore 

 to secure its- complete volatilization and estimation in the distillate. 

 The experiments which I proceed to describe are the result of an 

 effort to accomplish this end. 



Aside from the difficulties in manipulation and in the construction 

 of apparatus which the use of hydrofluoric acid would involve, this 

 reagent is otherwise plainly inapplicable to the purpose in view, and 

 of other agents with which boric acid is known to volatize freely 

 methyl alcohol seems to present the most desirable qualities. Methyl 

 alcohol, ethyl alcohol, and water are effective in the order in which 

 they are named. Thus, to volatilize 1 grm. of boric acid, — the equiv- 

 alent, speaking roughly, of about 0.5 grm. of boric anhydride, — two 

 treatments with 10 cm.^ of methyl alcohol and evaporation to dryness 

 in each case were adequate ; for the volatilization of 0.2 grm. of boric 

 acid were required two treatments of 10 cm.^ each of ethyl alcohol, suc- 

 ceeding an evaporation with 50 cm.^ of the same alcohol ; and the 

 residue of five evaporations of water over 0.4 grm. of boric acid, taking 

 in each case 50 cm.^ of water, followed by ignition, weighed 0.08 grm., 

 or one fifth of the original weight. In the presence of water, methyl 

 alcohol is not equally effective; amyl alcohol and sulphuric acid restrain 

 its action similarly, doubtless by dilution simply, and hydrochloric acid 

 seems to possess no advantage over water alone in developing the 

 volatility of boric acid. As an example, an experiment may serve in 

 which a solution of 0.4 grm. of boric acid in 50 cm.^ of water, after 

 being heated three times successively with 25 cm.^ of methyl alcohol 

 until the boiling point rose in every case nearly to that of water, 

 and then evaporated to dryness, left a large residue which disap- 

 peared with a single charge of 25 cm.^ of methyl alcohol applied by 

 itself. 



From the residue of the evaporation of borax with hydrochloric, 

 nitric, or acetic acid, methyl alcohol, as would naturally be predicted, 

 volatilizes the boric acid freely, though the presence of foreign ma- 

 terial acts to a certain degree protectively and tends to diminish the 

 rapidity with which the alcohol would otherwise eflfect extraction and 

 volatilization. In case, however, that acetic acid is used to break up 

 the borate, the tendency of sodic acetate to lose acid and become alka- 

 line simply by exposure to evaporation in its aqueous solution makes 



