94, 95] The Sulphuric Acid Method 65 



tin. This substance, whilst not acted upon by ammonia, is a 

 far better conductor of heat than glass, so that a 1 2-inch con- 

 denser is perfectly effective, d is 

 a long test tube with a hole blown 

 through its end at b. It is fixed 

 to the end of the condenser by a 

 cork, and dips to within half-an- 

 inch of the bottom of the 8-oz. Fig 



conical flask e. 



94. When the apparatus is ready, proceed with the estimation 

 in the following manner : 



(a) Run 20 c.c. of seminormal sulphuric acid from a burette 

 into the flask e. Insert the test tube d and fix on to the con- 

 denser, as in the figure. 



(b) Half fill the can a with water, and set it to boil. 



(c) Pour about 100 c.c. of distilled water into the large flask b. 

 Then pour into this water the acid liquid in which the linseed 

 cake has been decomposed. Wash out the small flask three 

 times with water, and add the washings to the liquid in b. 



(d) Replace all the apparatus as in the figure. 



(e) Measure out 100 c.c. of the strong caustic soda solution 

 (357 grams per litre), and run it through the tap funnel, s, into 

 the flask. 



95. The distillation may now be proceeded with. Light 

 the lamp under a, and turn on the water through the condenser. 

 In a few minutes the liquid in b will be raised to the boiling- 

 point. Allow the steam to pass for twenty-five minutes, then 

 light the rose burner g. Let the steam pass for five minutes 

 more, and the distillation will be completed. 



Remove the test tube d and flask e from the condenser. 

 Take the tube from the flask, washing back the adhering acid. 

 Add a drop or two of methyl orange, and titrate with standard 

 KHO. 



F 



