Chemical Science, 445 



tain water of crystallization, others none. The dry salts are decom- 

 posed by heat into carbonatea and charcoal. The sulphuric, nitric, 

 and muriatic acids decompose these salts, producing carbonaceous 

 precipitates. The neutral salts reduce nitrate of silver and muriate 

 of gold. 



Amylic acid dissolves carbonate of lime, with effervescence. Tlie 

 solution evaporated yields octangular crystals, mingled with plates. 

 The salt is soluble in 4 parts of water, and scarcely in alcohol. Its 

 solution is decomposed by oxalate of potash. It consists of 42.16 

 of lime, and 57,84 of amylic acid. 



The amylate of baryta, obtained in a similar way, exists in qua- 

 drilateral prisms, and consists of 57.29 baryta, 29.24 amylic acid, 

 and 13.47 water. The salts of potash, soda, and ammonia, are 

 dehquescent. 



Amylic acid consists of 2.5 carbon, and 3 oxygen. — Trommsdorff, 

 Neues Journal, — Bull. Univ. A. x. 171. 



30. Pinic Acid, a constituent of Venice Turpentine. — In a long 

 and interesting memoir on resins, contained in the Annalen der 

 Physik und Chemie, for 1827, M. Unverdorben states, that Venice 

 turpentine is composed of, i. A large quantity of volatile oil ; 

 ii. Of an oil less volatile and strongly retained by the resins present ; 

 iii. Of much resin, or pinic acid ; iv. Of another resin dissolving in all 

 proportions in alcohol, ether, oils, and even naphtha, and not capable 

 of combining with alkalis or metallic oxides ; v. Of a little succinic 

 acid ; vi. A small quantity of bitter extract ; and vii. Of traces of a 

 resin insoluble in petroleum. 



When Venice turpentine has been distilled with 20 parts of 

 water, until half the water has passed over, and this operation has 

 been repeated several times, a semi-viscid mixture of resin with oils 

 is left in the retort. This dissolved in alcohol of 65 per cent, gives 

 a green precipitate with an alcohol solution of acetate of copper. 

 This precipitate is pinate of copper, which being washed on a filter 

 with alcohol, and then dissolved in alcohol with a little muriatic 

 acid, may have the pinic acid precipitated by water as a white 

 resinous and transparent substance. Being then washed with 

 boiling water, the alcohol is removed, and it becomes a solid, inodo- 

 rous and almost insipid body. 



The pi7iic acid, in alcoholic solution, is gradually altered by ex- 

 posure to air ; it is also affected by heat ; it forms only neutral 

 combinations ; these are most soluble in pinic acid, and also in 

 alcohol. The pinates of potash and soda are obtained by slowly 

 boiling an etherial solution of pinic acid, for a few minutes, witli 

 the alkaline carbonates, filtering and evaporating the solutions : the 

 residuum is the alkaline pinate, a resinous, colourless mass, which 

 dissolves completely in boiling water. The pinate of potash is 

 precipitated from its concentrated solution, not only by an excess 

 of potash or soda, but also by neutral salts, as sulphate of soda, 

 muriate of soda, acetate of potash, &c. 



OCT.— DEC. 1828. 2 H 



