Intelligence and Miscellaneous Articles. 385 



INFLUENCE OF MAGNETISM UPON CHEMICAL ACTION. 



The Abbe" Rendu, professor of physics at Chambery, communicated 

 to M. Biot the following experiment. " I took," says he, " a tube 

 bent in the form of a V, its diameter was about a millimetre (nearly 

 t £tt of an inch) j each leg was 60 millimetres long. I filled the tube 

 with tincture of red cabbage, and placed an iron wire in each leg ; one 

 of these wires was supported by the north pole, and the other by the 

 south pole of a horse-shoe magnet. In a quarter of an hour from the 

 commencement of the experiment the colour of the tincture was 

 changed to a fine green, the same change occurring in both legs of 

 the tube." 



On repeating this experiment at the desire of M. Biot with an 

 important modification, which consisted in placing the two iron wires 

 suspended from the poles of the magnet in two small glass tubes closed 

 at the ends, which were immersed in the liquid, M. Rendu obtained 

 the same results, except that the blue tincture did not become green 

 until after two days j but the colour was as intense as in the first ex- 

 periments. The alteration of colour did not result from any sponta- 

 neous change in the liquid, for this solution left to itself, became red 

 and not green*. — Ibid, xxxviii. 196. 



INFLUENCE OF GUM-ARABIC IN THE PRECIPITATION OF LEAD 

 BY SULPHATES. 



According to Mr. A. J. Walcker, sulphate of soda after a few 

 minutes produces a precipitate in a solution of crystallized acetate 

 of lead, when it constitutes ,y p a part of the solution. But when 

 water at the same time contained -^V of its weight of gum-arabic, a 

 precipitate was only obtained with lu Vp of the acetate. With x s ' u - 

 of the acetate there was no precipitation even after a few hours, and 

 the same was the case when the liquid contained T V of gum-arabic, 

 and the acetate amounted to t-oV-o-. The cause of this anomaly 

 cannot be ascribed to the suspension of the precipitate by the viscid 

 fluid ; for neither standing for a few days nor boiling assists the ef- 

 ficacy of the precipitant, whilst a few drops of acetic, nitric, or sul- 

 phuric acid, instantly occasions precipitation. — Roy. Institute Journ. 



COMBINATION OF CHLORINE WITH PRUSSIATE OF POTASH. 



Mr. James F. W. Johnston, A.M. has a paper on the above-named 

 subject, of which the following is an extract : 



" The new compound described in this paper is considered as a 

 chloro-ferro-cyanide of potassium, and consists of 



1 atom chloro-ferro-cyanic acid. ... = 31 J -* 

 4 potassium = 20 > 



" This new acid may be obtained in a separate state by various 

 processes, which Mr. Johnston promises to explain in a future 

 paper. When pure, it forms beautiful red four-sided needles, not 

 differing in appearance from those of any of its salts. 



* Some former experiments on this subject are mentioned in the Annalcs, 

 of which we shall give an account in our next Number. — Edit. 



Nnv Series. Vol. 4. No. 23. Nov. 1828. 3D " Mr, 



