ANALYSIS OF BUTTER-FAT. 51 



in the case of butter-fat, evinced by the strong agreeable 

 smell of butyric ether evolved, resembling the odour of pine- 

 apples. 



After a minute or two, a few drops of distilled water are 

 added to the alcoholic liquid. If, thereby, a turbidity makes 

 its appearance, caused by undecomposed fat, the liquid is 

 heated a little longer, the turbidity dissolving in the excess 

 of alcohol. Small quantities of distilled water are added 

 from time to time, until a considerable addition of it to the 

 solution of soap no longer causes any precipitate of fat. It 

 must be remembered that water takes part in the reaction 

 which ensues, and if the alcohol be too strong, even the 

 most prolonged heating would not effect perfect saponifi- 

 cation. 



Another mode of procedure is to make a saturated solution 

 of caustic potash or soda in alcohol, and use about 5 c.c. of 

 this solution. This has some advantage over the addition of 

 the solid alkali, as spurting is not so likely to happen, and 

 the introduction of impurities hidden in the stick potash or 

 soda is impossible ; besides which carbonates, if present, are 

 precipitated in the alcohol, and any danger of effervescence 

 which may be caused by the escape of carbonic acid when 

 the acid is added, and which may render the decomposition 

 too violent, is also avoided. When the alkali is added in 

 alcoholic solution, the whole may be allowed to evaporate to 

 dry ness, providing that the water-bath be not too hot, 

 without danger of loss by spurting, and usually a clear .soap 

 solution is obtained when water is added. 



Saponification is complete when any amount of dilution 

 does not alter the transparency of the liquid. Should it 

 happen that the water has been added too quickly (which 

 can only occur if the necessary care has not been bestowed 

 upon the process), fat separates in the form of oily droplets, 

 which now no longer dissolve in the too dilute alcohol. In 



