LABOEATORY AND GREENHOUSE STUDIES. 97 



on warming the mixture indicated the absence of any aldehydes. 

 From this distillate the presence of alcohol only was thus demon- 

 strated. 



PRODUCTION OP VOLATILE AND FIXED ACIDS. 



The residue from the distillate for alcohol was used for detection of 

 acid production. The flask was disconnected from the condenser and 

 the calcium carbonate filtered from the residue. Ten cubic centimeters 

 of concentrated hydrochloric acid were then added to this filtrate 

 and mixed well. The calcium remaining in the filtrate was precipi- 

 tated by adding sodium carbonate solution to alkalinity. The mix- 

 ture was thoroughly boiled to insure complete precipitation. It was 

 then filtered and 20 c. c. of 25 per cent sulphuric acid were added to 

 the filtrate for the purpose of liberating the volatile acids; finally the 

 filtrate was ciistilled as completely as possible. (This distillate will 

 contain the volatile acid, if one be present.) The solution was first 

 saturated with baryta water to alkalinity and then evaporated to 

 dryness. To this 20 c. c. of absolute alcohol were added, and it was 

 allowed to st£ind with frequent stirring for about three hours, when 

 it was filtered and washed with alcohol. This last filtrate should 

 contain barium propionate and barium butyrate, if present. The 

 filtrate was evaporated to dryness; the residue was dissolved in 150 

 c. c. of water and saturated with calcium chlorid. It was then dis- 

 tilled and the distillate tested for butyric acid. Three cubic centi- 

 meters of alcohol and four drops of concentrated sulphuric acid were 

 added to a part of the solution, but there was no resultant pineapple 

 odor to indicate the presence of butyric acid. The propionic acid 

 was not given a special test. 



The residue from the alcohol washing described in the previous 

 paragraph was treated for barium acetate and barium formate. It 

 was first dried, and the residue dissolved in the filter in hot water, 

 and the resultant solution was divided into four portions. To one 

 portion was added ferric-chlorid solution, and the absence of any 

 brown color gave negative results for the presence of acetic or formic 

 acid. To another portion silver-nitrate solution was added and then 

 one drop of ammonium water, and the solution was boiled. A black 

 precipitate resulted from this, which indicated the presence of formic 

 acid. To another portion a few drops of mercuric-chlorid solution 

 were added and heated to 70° C. There was, however, no distinct 

 precipitate of mercurous chlorid nor a formation of a metallic mirror. 

 Thus, the tests suggested the presence of formic acid without abso- 

 lutely proving it, while they indicated the absence of acetic acid. 



The residue remaining from the distillation of the mixture after 

 the addition of sulphuric acid was tested for the fixed acids. It was 

 evaporated to a syrup and then extracted with ether by agitation in 

 6389°— Bui. 228—12 7 



