SODA LYE. 

 CARBONATE AND HYDROXID, METHOD I (PROVISIONAL). 



SOLUTIONS REQUIRED. 



A half-normal solution of hydrochloric acid; methyl orange and phenol- 

 phthalein indicators. 



METHOD. 



A large quantity of the sample is weighed out in a weighing bottle, dissolved 

 in water previously boiled to get rid of carbon dioxid and made up to a 

 definite volume. Aliquot portions of this are taken for analysis. One portion 

 is titrated with half-normal acid, using methyl orange as indicator, and the total 

 alkalinity thus found noted. Another aliquot portion of the same size is trans- 

 ferred to a measuring flask, and enough barium chlorid added to precipitate 

 out all carbonate, avoiding any unnecessary excess. The volume is made up to 

 the mark with carbon-dioxid-free water, stoppered, shaken, and set aside to 

 allow the precipitate to settle. When the liquid becomes clear one-third of it 

 is drawn off by means of a pipette and titrated with half-normal hydrochloric 

 acid, using phenolphthalein as indicator. This number of cubic centimeters of 

 half-normal acid multiplied by 3 gives the number of cubic centimeters of half- 

 normal acid corresponding to the original amount taken. The last figure 

 obtained represents sodium hydroxid, and the difference between the first and 

 last figures represents the sodium carbonate. 



CARBONATE AND HYDROXID, METHOD II (PROVISIONAL). 



SOLUTIONS REQUIRED. 



A fifth-normal solution of potassium acid sulphate ; methyl orange and phenol- 

 phthalein indicators. 



METHOD. 



The lye is weighed out and dissolved to a definite volume in carbon-dioxid- 

 free water just as described in Method I. An aliquot portion is taken, diluted 

 with carbon-dioxid-free water and a few drops of phenolphthalein added. A 

 fifth-normal solution of potassium acid sulphate is added at the rate of about 1 

 drop per second, with constant stirring, until the pink color fades out and the 

 solution becomes colorless. The reading thus obtained, which we will call n, 

 represents the sodium hydroxid and one-half of the sodium carbonate present 

 since the sodium carbonate is changed to sodium bicarbonate. Methyl orange 

 is added and the titration continued to the appearance of a pink color. Let 

 this number of cubic centimeters be represented as m. Since this last 

 titration represents the sodium bicarbonate present, or one-half the sodium 

 carbonate, 2m represents all the sodium carbonate present and n m the sodium 

 hydroxid. 



TOBACCO AND TOBACCO EXTRACTS. 

 NICOTIN, METHOD I (OFFICIAL). 



SOLUTIONS REQUIRED. 



An alcoholic soda solution containing 6 grams of sodium hydroxid, 40 cc of 

 water, and 60 cc of 90 per cent alcohol. A weak sodium hydroxid solution con- 

 taining 4 grams of sodium hydroxid in l,000cc of water. A standard sulphuric 

 acid solution. 



