Chemical Science. 413 



iNI. Berzelins describes two muriates of gold. The super- 

 muriate crystallizes readily in small needles, of a pale-yellow 

 colour; it is less soluble in water than the neutral muriate, and 

 its solution is of a gold-yellow colour. The neutral muriate is 

 obtained by exposing the super-muriate to a low heat. It loses 

 first muriatic acid, and then a mixture of it with chlorine, so 

 that it begins to decompose even before all the free acid is 

 driven off. To obtain it perfectly neutral, it must be prepared 

 l)y adding hot wafer to the proto-muriate of gold, which is then 

 reduced to gold and the neutral muriate. Its solution is of an 

 intense ruby colour ; it yields a reddish-brown saline mass, 

 which liquifies in the air. The addition of muriatic acid 

 changes the colour to yellow, and per-muriate crystallizes, if 

 the solution is concentrated. — A7in. de Cliem. xviii. p. 146. 



9. On. rendering Tissues incombustible. — M. Gay-Lussac men- 

 tions, as the result of his experiments on the best means of 

 rendering cloth incombustible, that solutions of muriate, sul- 

 phate, phosphate, andl)orate of ammonia, with borax, and some 

 mixtures of these salts, were found the most effectual; in fact, 

 according to his theory on the subject, those substances which 

 at the temperature of burning best shielded the fibre from the 

 air, and supplied most incombustible gas or vapour to the 

 flame, proved to be most efficacious. 



10. Heat produced by Chlorine. — Among the obvious quali- 

 ties of chlorine, Dr. Silliman mentions the heat it excites on 

 the hand when plunged into it. The effect is equal to a tem- 

 perature of 90° or 100°. 



U. Explosion of Chlorine and Hydrogoi. — Dr. Silliman cau- 

 tions chemists against making mixtures of chlorine and hydro- 

 gen in large quantities without due precaution. He relates 

 some instances in which two or three quarts of the gases had 

 been mixed, where the explosions produced on exposure to 

 sunlight were instantaneous and very powerful, and one also in 

 which the explosion took place by exposure of the gases to a 

 very diffuse and dim light. 



12. Oxalic Acid. — M. Berzelius decomposed the oxalic acid 

 by first forming an oxalate of lime of determinate composition, 

 as to the water it contained, and then digested it with mu- 

 riate of gold. The gold was reduced, and carbonic acid 

 formed, .4 grains of oxalate, containing 3.25 of the anhydrous 

 compound, reduced 3.3.02 grains of metallic gold, from which 

 the composition of oxalic acid is deduced as 2 atoms of carbon 

 and three atoms of oxygen, no hydrogen being present. 'I'his 

 result was confirmed by the action of the quadroxalate of po- 

 iHhsa on bululion of gold ; 2 grains of it precipitate 2.05 of the 

 metal. 



