CALCAREOUS MANURES— APPENDIX. 17 J 



muriatic acid, lie has mixed tlie waslied geine witli a little nitrate of silver. 

 After evaporation to dryness, and calcination, the residue, treated by nitric 

 acid, was dissolved, w^ithout leaving any muriate of silver. But as muriate 

 of silver, like the other salts of silver, is reduced to a metallic state by 

 bodies containing carbon and hydrogen, and carbon itself effects the same 

 change when disengaged along with water, this result proves nothing. In 

 general, in the descriptions of geine, they have attributed the properties of 

 that which has been changed by the action of an alkali, to the geine which 

 has not been altered. The geine which reddens vegetable blues, is the 

 same, whatever may have been the acid which served for its precipitation. 

 Its saturated aqueous solution is of a yellowish brown, and the combina- 

 tion is precipitated anew by acids, excepting the carbonic, and the sulphur- 

 etted hydrogen. Collected upon a filter, it is presented under the form of 

 a gelatinous mass, of a taste slightly acid, astringent — and by drying, it 

 contracts strongly, and forms clots of a deep brown, almost black, with a 

 vitreous fracture, and which are not dissolved again in water after being 

 once completely dried. The aqueous solution of the acid geine, is precipi- 

 tated by the salts of lead, of tin, and of iron ; but is not disturbed by gela- 

 tine, albumen, starch, gum, tannin, or solution of soap. According to 

 Braconnot, it is precipitated by a mixture of the solution of gelatine and 

 gallic acid. The dried geine is dissolved with difficulty, and incompletely, 

 in alcohol. The solution reddens vegetable blues, whilst the part not dis- 

 solved is without this power, though it still preserves the property of com- 

 bining with potash. Geine is destroyed by concentrated acids. The sul- 

 phuric acid dissolves it, taking at the same time a black color, carbonizing 

 it, disengaging sulphurous acid gas, and leaving for residue the ordinary 

 products which result from the action of this acid. By the addition of sur- 

 oxide (or black oxide) of manganese, carbonic acid gas is disengaged. 

 The nitric acid dissolves and decomposes geine, with a disengagement of 

 nitric oxide gas, and carbonic acid gas. If the solution is evaporated to 

 the consistence of syrup, and then mixed with water, there is precipitated a 

 peculiar bitter substance in powder, and there are found in the solution, 

 artificial tannin and oxalic acid. 



Geine forms soluble combinations with alkalies. When an excess of 

 geine is used, the caustic alkalies are so neutralized by this substance, that 

 they lose their peculiar chemical action and properties. In this respect, 

 geine agrees with gluten, vegetable albumen, the brown of indigo, the sugar 

 of liquorice, apotheme, and other bodies not acid. During the evaporation 

 the solution furnishes a black mass, which acquires lustre by complete dry- 

 ing, and splits, and is easily reduced to a powder. It is redissolved in wa- 

 ter, its taste is weak, bitter and disagreeable. Caustic ammonia gives a 

 like mass, soluble in water, which gives up, during evaporation, the excess 

 of alkali employed. Geine is not dissolved always in alkaline carbonates ; 

 when it is so dissolved, these carbonates are transformed, half into geaies, 

 half into bi-carbonates. When the solution is boiled, the bi-carbonate is 

 decomposed with disengagement of carbonic acid gas, and in this manner 

 the geine drives off all the carbonic acid. If a solution of geine in car- 

 bonate of ammonia is evaporated, a residue is obtained containing neu- 

 tralized geate of ammonia. The solution of geine in caustic potash, in ex- 

 cess, absorbs oxygen from the air, and at the end of some time, the alkali 

 is in part carbonated. 



Geine forms with the alkaline earths pulverulent combinations but little 

 soluble, which have an external resemblance to geine. The best means for 

 obtaining them is to mix a solution of the geate of ammonia, with the solu- 



