LARD AND LARD ADULTERATIONS. 



455 



B. CHEMICAL PROPERTIES. 



(a) Volatile or soluble and insoluble acids. The determination of the 

 volatile acid is made in the apparatus represented in Fig. 24. The solu- 

 ble acid may be estimated by the process described in Bulletin No. 16, a 

 resume of which follows.* 



OHE/OEMftM.SC 



W SCROLL. 



FIG. 24. 



METHOD FOR THE DETERMINATION OF SOLUBLE AND INSOLUBLE ACIDS. 



Reagents. (1) A standard semi-normal hydrochloric- acid solution, 

 accurately prepared. 



(2) A standard cleci-normal soda solution, accurately prepared ; each 

 Ice. contains .0010 grams of NaOH and neutralizes .0088 grains of 

 butyric acid, C 4 H 8 O 2 . 



(3) An approximately semi-normal alcoholic potash. Dissolve 40 grams 

 of good stick potash in 1 liter of 95 per cent, alcohol, redistilled. The 

 solution must be clear and the KOH free from carbonates. 



(4) A 1 per cent, solution of phenolphthalein in 95 per cent, alcohol. 

 Sapouification is carried out in rubber-stoppered beer bottles hold- 

 ing about 250 cc, or in a round-bottom strong flask used iu distillation. 



About 5 grams of the melted butter fat, filtered and freed from water 

 and salt, are weighed out by means of a small pipette and beaker, which 



* Bulletin No. 16, page 70. 



