224 ANNUAL OF SCIENTIFIC DISCOVERY. 



butyric acid ether, in 8 to 10 parts of spirits of -wine. For preparing 

 butyric acid ether, pure butyric acid is required, and this is obtained 

 most readily, and in the greatest purity, by the fermentation of sugar 

 or of St. John's bread, (siliqua dulcis!) For preparing butyric acid 

 from sugar, M. Bentch takes a solution of 6 pounds of sugar, and half 

 an ounce of tartaric acid in 26 pounds of water, which is left to stand 

 for some days ; at the same time about a quarter of a pound of old 

 decayed cheese is diffused in 8 pounds of sour milk, from which the 

 cream has been removed ; and after this has also stood for some days, 

 it is mixed with the first solution, and the whole is kept from four to 

 six weeks at a temperature of about 24 to 28 Reauiner, water being 

 added from time to time to replace that which is lost by evaporation. 

 After the evolution of gas has entirely ceased, the liquid is dissolved 

 with its own bulk of water, and finally 8 pounds of crystallized soda, 

 dissolved in 12 pounds to 16 pounds of water, are added to it. The 

 liquid is then filtered and evaporated till it weighs only 10 pounds, 

 when a quantity of 5j? pounds of sulphuric acid, (nordhausen, or fum- 

 ing sulphuric acid,) diluted with 5| pounds of water, is carefully 

 mixed with it by small portions at a time. The butyric acid, in the 

 state of an oily substance, will now appear on the surface of the liquid, 

 from which it may be skimmed off ; but as the remaining liquid still 

 contains some butyric acid, it is submitted to distillation, by which 

 means another portion of diluted butyric acid is obtained, which may 

 be concentrated by means of melted chloride of calcium, or by satu- 

 rating it with carbonate of soda, evaporating and decomposing by 

 1 sulphuric acid. By this method If pounds of pure butyric acid are 

 obtained from 6 pounds of sugar. 



M. Marsson says that the same product may be obtained from St. 

 John's bread, (siliqua dulcis,') by taking 4 pounds of mashed St. John's 

 bread, and mixing it with 10 pounds of water and 1 pound of chalk ; 

 the liquid matter must be maintained from three to four weeks at a 

 temperature of frQni 25 to 35 Reaumer, and be often and well 

 stirred, and from time to time the water that has evaporated must be 

 replaced. After all fermentation has ceased, a quantity of water equal 

 to the bulk of the liquid is added to it, and afterwards a concentrated 

 solution of 2| pounds to 2f pounds of carbonate of soda, when it is 

 finally evaporated. To the concentrated liquid is then added 1^ 

 pounds to 2 pounds of sulphuric acid, diluted with 2 pounds of water; 

 and the remainder of the process is performed in the same manner as 

 already described. By this method a little more than hah a pound of 

 colored butyric acid will be obtained. The acid, however, retains a 

 peculiar smell from the St. John's bread, which continues even in the 

 ether prepared from the same, whereas that prepared from sugar gives 

 an ether of a very pure smell. It will be found advantageous to agi- 

 tate the oily butyric acid with chloride of calcium, in order to deprive 

 it entirely of its moisture. 



For preparing butyric acid ether, (butyrate of oxide of ethyle,) 

 from butyric acid, 1 pound of butyric acid is dissolved in 1 pound of 

 rectified alcohol, (95 Tralles,) and is mixed with one-half to one- 



