218 ANIMAL AMIDES. 



it dissolves when assisted by heat When this solution is boiled 

 for some time the gelatin is converted into starch sugar. Nitric 

 acid dissolves the gelatin at the ordinary temperature of the at- 

 mosphere. When heat is applied deutoxide of azote is given 

 out and oxalic acid formed. In concentrated muriatic acid it 

 dissolves without any change of colour. In phosphoric acid it 

 dissolves, and if the solution be heated it blackens. 



The solution in concentrated acetic acid forms when evaporated 

 a thick mass. When we mix it with water, no precipitate falls. 

 But prussiate of potash throws down a fine green precipitate, 

 which is soluble in water. 



It dissolves in potash, soda, and ammonia, but is thrown down 

 by acids. The solution in acid is also precipitated by alkalies, 

 but the precipitate is again dissolved by adding an excess of po- 

 tash. We see from this that the gelatin is insoluble in solutions 

 of neutral salts with alkaline bases. It is soluble by boiling in 

 carbonate of potash. When acetic acid is added to this solution, 

 no disagreeable smell is evolved ; nor does the liquid become 

 black when silver is added to it. 



When the aqueous solution is concentrated and set aside to 

 cool, it gelatinizes a white precipitate falls, when the following 

 liquids are added to the aqueous solutions of this gelatin ; -alcohol, 

 infusion of nut-galls, protonitrate of mercury, diacetate of lead, 

 chloride of tin, chlorine water, bromine. The chloride of gold 

 throws down a yellow precipitate. 



The following liquids occasion no precipitate when added to 

 an aqueous solution of gelatin : oxalic acid, acetate of lead, cor- 

 rosive sublimate, nitrate of silver, nitrate of cobalt, cyanodide of 

 mercury, perchloride of iron, chloride of barium, sulphate of 

 potash, iodide of sodium, sulphohydrate of ammonia, acetate 

 of copper, tartar emetic, borax, persulphate of iron. When iodine 

 is triturated with the aqueous solution of gelatin, no action is 

 perceptible, 



It was analyzed by Mulder, who found its constituents (ab- 

 stracting 5-2 per cent, of ashes), 



Carbon, . 49-49 

 Hydrogen, . 5*98 

 Azote, . 19-19 



Oxygen, . 25-34 



100-00 



