FATS. 79 



ment of hydrogen lias ceased, the operation is at an end, and 

 the solntion tlien contains only butyi'ate of lime/' 



The composition of butyric acid, its proportion which 

 amounted in several experiments to above the third of the 

 weight of the sugar, the hberation of free hydrogen, and of 

 carbonic acid (independent of that which is disengaged from 

 the chalk,) admit of our supposing that, under the prolonged 

 influence of ferments, sugar is decomposed in the following 

 manner : 



Grape-sugar. Butyric acid. 



C„H,, O,, = C8H7O3 + HO + 4CO, + 8H + 2HO. 



This formula is merely intended to exhibit the final result, 

 for several chemical processes^ precede the formation of butyric 

 acid. 



By combining the butyric acid formed in this manner with 

 glycerin, they obtained a fatty matter that seemed in all 

 respects identical with butjTin, as described by Chevreul. 



Fibrin ^aelds butyric acid as one of the products of its 

 decomposition : the other products of its putrefaction are 

 albumen, carbonic and acetic acids, and ammonia. It may like- 

 wise be obtained by heating this substance with potash at a tem- 

 perature of from 320" to 356". A small quantity of a volatile 

 fatty acid forms, which remains in combination with the potash, 

 whilst ammonia and other volatile products are disengaged. 

 This acid has not yet been analysed, but it seems to possess all 

 the properties of butyric acid. (Wurtz.) 



Caproic acid is obtained from the caproate of baryta, which 

 crystallizes in long silky needles, aggregated into bundles. 



It is an oily limpid liquid with the odour of sweat, and a 

 sharp acid taste. Its spec. grav. is 0*922 at 72" ; it evaporates 

 in the open air ; its boiling point is above 212", and it is soluble 

 in 96 parts of water at 44"* 6. It dissolves in alcohol and 

 ether. 



' It is well known that if a small quantity of casein be introduced into a solution 

 of cane-sugar or sugar of milk, lactic acid begins very soon to be formed. The 

 butyric acid may be supposed to be formed in the following manner : 

 20 eq. of lactic acid (C^^g H,2o 0,oo) = 15 eq. of butyric acid (C,2o Hu^ Ogo) + 60 O. 



These 60 eq. of oxygen decompose 6 eq. of lactic acid, and we have — 

 6 (Cg Hg Oe) + 60 = C36 Hgg 09^ = 3 CO., + 12 H -f 24 HO 

 when the carbonic acid is exactly three times the volume of the hydrogen produced. 



