360 Messrs. Wanklyn and Cooper on the 



baryta, and final organic acid will be noted. The want 

 of accordance between the quantity of baryta-salt taken and 

 the quantity required by the equation, as will be understood, 

 means that the salt was not in a state of absolute dryness. 

 The correctness of this interpretation was borne out by the 

 observation that on ignition the acid left no appreciable fixed 

 residue, viz. 0*774 grm. of the solid acid left, on careful 

 ignition, 0*002 grm. of ash. The acid was also ascertained to 

 be free from sulphuric acid. 



Properties of Cyano-propionic Acid. — It is an amorphous 

 solid, brittle at ordinary temperatures, but easily softening on 

 being heated to 100° C. Its colour is pale brownish yellow, 

 or straw-colour ; in powder it is almost white. 



It is very soluble in water and in strong alcohol. Its 

 aqueous solution is powerfully acid, both to the taste and to 

 litmus. It drives out carbonic acid from carbonates, and neu- 

 tralizes bases completely. 



The specific gravity of an aqueous solution of the acid con- 

 taining 15-12 per cent, of (C 4 H 5 lsr0 2 ) 2 , 3H 2 0, is 1*06 at ordi- 

 nary temperatures. An aqueous solution of one tenth of this 

 strength, viz. containing 1*512 per cent., forms a lather on 

 being shaken up, is pleasantly acid to the taste, and is capable 

 of dissolving metallic magnesium in the cold. In presence of 

 metallic mercury the action of the magnesium is brisk; and in 

 the space of twenty-four hours ten cubic centimetres of the 

 weak acid liquid confined over mercury had evolved almost 

 the theoretical quantity of hydrogen which the magnesium 

 was capable of displacing. 



Cyano-propionic acid is attacked when it is sealed up in a 

 tube with the acid 8-per-cent. bichromate solution and heated 

 to 100° C. Under these conditions very little oxygen is taken 

 up and carbonic acid is formed in considerable quantities. 



In alkaline solution, when boiled with permanganate of 

 potash, it is slowly attacked, and takes up one third of its 

 weight of oxygen. When heated to about 200° C. with great 

 excess of potash, it suffers a very interesting decomposition, 

 which we are at present investigating. 



When the acid is heated above 100° C. it loses weight, and 

 becomes constant at about 140° C. After repeated heating to 

 that temperature, the formula of the acid (judging by the loss 

 of weight) appears to be C 4 H 5 N0 2 . At temperatures above 

 140° C. the acid continues to lose in weight, but apparently 

 undergoes decomposition, inasmuch as it evolves a very pecu- 

 liar smell, reminding us of cyanide of ethyl. A portion of the 

 acid which had been dried at 140° C. lost about half of its 

 weight when heated to 220° C, and yielded a brown or black 



