BORIC ACID AND BICARBONATE. 61 



acid ester is formed. If the alcohol be ignited a flame 

 tinged with green is produced. 



For the quantitative determination of boric acid Cassal 

 proposes the following process : loo grams of milk are 

 hiade alkaline with sodium hydrate, evaporated and in- 

 cinerated. The ash is washed with water and methyl 

 alcohol into an Erlenmeyer flask fitted with a two hole 

 stopper. Through one of the holes is placed an adapter 

 projecting a short distance into the neck of the flask and 

 connected with a condenser. Through the other hole 

 is placed a separatory funnel filled with methyl alcohol. 

 The contents of the flask are acidified with acetic acid 

 and placed in an oil bath and subjected to distillation. The 

 distillation product is collected in a platinum crucible 

 filled with pure quicklime. This is placed in a large glass 

 beaker which is covered with a glass plate with a hole in 

 the center. Before using, the crucible and contents 

 should be ignited and weighed. Through the perforation 

 in the plate a bent glass tube connected with the free 

 end of the condenser is passed, allowing it to extend 

 down to the crucible. The distillation is repeated about 

 ten times, shaking each time with 5 c. c. of methyl alcohol. 

 The crucible is finally dried and heated strongly with al 

 blast. The increase in weight gives the amount of boric 

 acid in 100 c. c. of milk. 



II. SODIUM CARBONATE. SODIUM BICARBONATE. 



Ten c. c. of milk are mixed with 10 c. c. of alcohol (96 

 per cent) and a drop of rosolic acid solution (i :ioo). 

 Pure unadulterated milk produces a brownish-yellow 

 color, but in the presence of sodium carbonate or sodium 

 bicarbonate a rose color is obtained. For greater pre- 

 cision in doubtful cases the questionable sample should be 



