APPENDIX 

 PREPARATION OF STANDARD SOLUTIONS 



As the preparation of a standard solution is rarely, if 

 ever, undertaken while an analysis is being performed, 

 and as also it is tedious to wade through a description 

 of a method when seeking only for the quantities to be 

 weighed or measured for the solution, details of the 

 preparation have been removed from the text ; the 

 arrangement is alphabetical. 



Alcoholic Soda Solution. ^approximately. Add 



25 c.c. of a 50 per cent, caustic soda solution (see 

 p. 93) to i litre of alcohol (sp. gr. 0.830) and mix well ; 

 allow the solution to stand a day, filter into a dry 



N 

 stoppered bottle, and titrate (see Titration) against 



hydrochloric acid (see p. 92) to ascertain strength. 

 As this solution loses strength on keeping, it must be 

 titrated each time it is used. 



Amyl Alcohol (for Gerber test) should conform to 

 the following : Density, 0.8145 to 0.816 at 15.5 C. 

 (Water at 15.5 C. = i.) Boiling-point : should not 

 begin to boil below 124 C. ; not more than 5 c.c. should 

 distil at 127.5 C. when 25 c.c. are boiled in a 100 c.c. 

 flask, and the boiling-point should not rise above 

 130.5 C. ; 10 c.c. should completely mix with 10 c.c. 

 of hydrochloric acid (sp. gr. 1.17) and the addition 

 of 1.5 c.c. of water should produce a permanent 

 turbidity. 2 c.c. treated in the Gerber bottle with 

 10 c.c. water and 10 c.c. sulphuric acid should yield no 

 layer of " fat." 



Barium Chloride Solution, -.24.45 grammes of 



crystallised barium chloride are dissolved in I litre of 

 distilled water. 



91 



