APPENDIX. 



157 



The apparatus is then connected, as shown in the illustration, with the glass tube 

 dipping in the liquid in flask E. The stopcock B is then partly opened, and the acid 

 is allowed to flow in at such a rate that the bubbles pass through E about one per 

 second. Slowly increase the heat to boiling and distill about 50 cc. 



After the distillation, titrate the liquid in E with decinormal sulphuric acid and 

 phenacetolin, or, better, make it up to a definite quantity and take an aliquot part for 

 titration, stopping at the first appearance of the pink. The difference between the 

 amount of hydroxid shown by this last titration and that known to have been con- 

 tained in it previous to receiving the distillate is the amount of hydroxid that has 

 been converted into carbonate, and from this the quantity of carbon dioxid may 

 readily be calculated. A check on the work may be made by titrating the yellow 

 color, and the difference between the appearance of the pink and the appearance of 

 the yellow is the amount of hydroxid in combination with carbon dioxid. 



This method, for use in the determination of available carbon dioxid in baking 

 powder, could be modified by placing the powder in C without water and introduc- 

 ing water gradually through the funnel 



tube and afterwards heating it as de- IIA 



scribed. -/. C. Mims. 



Page 100, 1, (a), (3). It is conven- 

 ient to introduce sample wrapped in a 

 cartridge in tissue paper into the dry 

 fla.sk. The tissue paper may be col- 

 ored with litmus or strips of litmus 

 paper may be introduced at the same 

 time. When the baking powder is 

 badly made and contains excess of the 

 acid ingredient this is indicated by the 

 litmus remaining red at end of opera- 

 tion. Usually the sodium carbonate 

 is in excess, and the paper remains blue. 



Page 101, 1, (b), (3). I find that 4 

 grains of a baking powder may safely 

 and conveniently be employed in deter- 

 mining carbon dioxid. This reduces 

 the factor needed to convert to per- 

 centage and conduces, to accuracy. 

 With a maximum value for baking 

 powder this amount yields from 0.5 to 

 0.6 gram of carbon dioxid. 



Page 104, 2. I find it convenient to determine the excess of sodium carbonate 

 occurring in most baking powders by replacing the tubes after determination of the 

 available carbon dioxid, adding acid to the decomposing flask, and continuing the 

 operation without recharging. The carbon dioxid now obtained is that due to excess 

 of sodium bicarbonate. A. McGill. 



Page 104, 7. We desire to make the following preliminary announcement of a 

 method for the application of the polariscope to the estimation of tartaric acid in 

 commercial products: 



The commercial products containing tartaric acid fall into three classes, corre- 

 sponding to the three methods of analysis described below: 



Class I. Tartaric acid and mixtures containing alkaline tartrates and calcium 

 tartrate but no other optically active substances or materials capable of modifying 

 the rotation of tartaric acid in am n ion iacal solution (e. g., alum, iron). To this class 

 belong Iloclielle salt, potassium tartrate, cream of tartar, calcium tartrate, and many 

 effervescing i (reparations of the Pharmacopoeia. 



FIG. 7. Mims' apparatus for the determination 

 of carbon dioxid. 



