Fyro'Ciirie Acid, Sfc. 187 



The new fluid is also remarkable for its extreme volubil- 

 ity, a- hering very slightly to the sides of the cavities; and is 

 likevv.se distinguished by its optical properties. It exists 

 not in sufficient quantities to admit of chemical analysis. It 

 is almost always accompanied by another fluid like water, 

 wit; which it refuses to mix, and which does not percepti- 

 bly . xpand at the above mentioned temperature. 



f V a specimen of cymophane^ or ehrysoberyl, Dr. BrewS'> 

 ter has discovered a stratum of these cavities, in which he 

 has reckoned in the space of ith of an inch square, thirty 

 thou and cavities, each containing this new fluid ; a portion 

 oft! e fluid like water; and a vacuity besides. All these 

 vaf ities disappear simultaneously at a temperature of 83°. 



If such a fluid could be obtained in quantities, it is ob- 

 served, that its utility in the construction of thermometers 

 and levels would be incalculable. There are many cavities 

 in crystals, such as those opened by Sir Humphry Davy, 

 which contain only water, and which, of course never ex* 

 hibit any of the properties above described. 



Edm. Phil. Journ. 



6. Pyro-citric Acid. — A new acid has been thus named by 

 M. J. Lassaigne who discovered it. It is produced by the 

 distillation of citric acid. It is white, inodorous, and of a 

 strongly acid taste, and occurs generally in a white mass, 

 composed of flne small needles. It melts, and is converted 

 into very pungent white vapours, leaving traces of carbon. 

 It is very soluble in water and in alcohol. At 50° Fahr. 

 water dissolves one-third of its weight. It is composed ot 

 carbon 4'7.5, oxygen 43.5, hydrogen 9. = 100. With the 

 oxides it forms salts, differing in their properties from the ci- 

 trates. M. Lassaigne has examined the pyro-citrates of 

 potash, lime, barytes and lead. 



Journ. de Pharm. 



7. Hydro-carho-sulphuric Acid. — Dr. Zeise of Copen- 

 hagen has discovered and named this new acid, which bears 

 the same relation to sulphuret of carbon, that hydro-cyanic 

 acid has to cyanogen. It may be procured by pouring a 

 mixture of four parts of sulphuric acid and three of water, 

 on the salt of potash, and adding much water in a few sec- 

 onds. The acid collects at the bottonj, in a transparent 



