BILIARY CALCULI. 91 



gradually "converted into butyrate. When no more 

 gas is evolved dilute with water, precipitate with 

 sodium carbonate, filter, evaporate down and decom- 

 pose with rather dilute sulphuric acid. Separate off 

 the oily stratum of butyric acid, distil it with a little 

 sulphuric acid, digest with fused calcium chloride and 

 again distil, rejecting the first portions. 



2. Distil the vomited matters or intestinal discharges 

 of cholera patients (rice water) with sulphuric acid, 

 neutralise the distillate with soda, evaporate down, 

 decompose with sulphuric acid, and distil again. 

 Saturate the hot distillate with hydra ted oxyde of 

 copper, and let stand, when cupric butyrate will crys- 

 tallise, while cupric acetate will remain in solution. 



3. Butyric acid boils at 157 0. ; it has an un- 

 pleasant rancid smell; it is insoluble in water and 

 alcohol. 



4. To lead acetate solution add a little butyric acid 

 dissolved in water ; an oily precipitate of lead butyrate 

 will appear. 



5. To a solution of potassium or sodium butyrate 

 add cupric sulphate ; a green precipitate of cupric 

 butyrate will be formed soluble in hot water, and de- 

 positing in crystals on cooling. 



6. Heat a butyrate with alcohol and sulphuric acid. 

 Butyric ether, having a characteristic odour of pine- 

 apples, will be evolved. 



Calculi) biliary. Systematic analysis. 1. Heat a 

 portion of the calculus on platinum foil ; it burns with 

 a clear or sooty flame, and is almost entirely consumed. 



