412 Miscellaneous Intelligence. 



did precipitate the protosalts. By evaporation, the solution gave a 

 little Prussian blue, and then crystals, the summits of which were 

 quadrangular pyramids. By two or three crystallizations these were 

 rendered perfectly pure. 



The red ferro-prussiate of soda could not be obtained in a similar 

 way, but only by passing chlorine through the ordinary ferro-prus- 

 siate of soda, formed by digesting soda on Prussian blue. By a 

 similar process he obtained a red ferro-prussiate of ammonia, but 

 the compound was not permanent. — Jour, de Pharmacie. 



12. New Method of analysing Alloys of Copper and Silver. — 

 This method is proposed by Professor Zenneck, of Stutgard, and 

 is founded upon the constant quantities of hydrogen gas evolved 

 when either silver or copper is dissolved in pure strong muriatic acid. 

 The solution requires to be assisted by heat ; and when copper is the 

 metal operated with, the surface of the acid in contact with the 

 air must be covered by a layer of oil ; with these precautions, a 

 given weight of copper always gives out a proportionate and equiva- 

 lent quantity of hydrogen gas, and a given weight of silver also, 

 its determinate equivalent; being in bulk less than that evolved from 

 copper. The difference between the bulks of gas evolved by equal 

 weights of the two metals enables a careful experimenter to deter- 

 mine, from a given weight of alloy and the gas it evolves, the pro- 

 portions of silver and copper present. 



The instrument used by Professor Zenneck is a glass tube closed 

 at one extremity, and bent nearly to a right angle. It is expanded 

 in the angle in the manner well known to chemists, so that when 

 filled with liquid any acid rising from a solid piece of matter in the 

 angle should ascend into the closed branch. It is, in fact, a bent 

 tube pneumatic receiver. The process is fully detailed in M. Zen- 

 neck's paper, and also in the abstract given of it in the Bibliotheque 

 U?iiverselle, xli. p. 317 — but we do not think it necessary to de- 

 scribe more than the principle. There is no doubt the process will 

 succeed in careful hands ; but objections to it, as a ready and sure 

 method, quickly arise in the mind. 



13. Artificial Ultramarine. — By following Gmelin's process*, 

 M. Hermbstadt has obtained the most beautiful ultramarine ima- 

 ginable. He attributes the success of the operation principally to 

 the care taken to mix the silicate of soda and alumine in as moist a 

 state as possible. If they are too much dried before adding the 

 sulphur, the colour obtained is only a bluish-green. — Allg. HandU 

 Zeitung, 1829. 



14. Anew Earthy Thorina. — This new earth, thorina, is a recent 

 discovery made by Berzelius, and must be distinguished from the sub* 



* Quarterly Journal, N. S, vol. iv, p. 216. 



