, Electricity-^Chemistry. 365 



1'his large column of water was inflected like a riband exposed to the 

 wind. In eight minutes it reached the mouth of the Rhone, and as long 

 as it was above the river, the boiling continued and the column was un- 

 broken. When it quitted the river the boiUng ceased, and the whole soon 

 disappeared, the base of the cone continuing longest visible.— ^zZ*/. Univers. 

 October 1827, p. 142. 



ELECTRICITY. 



11. Different effects of an electric discharge in Magnetising different 

 needles. — M. Savary, whose electrical discoveries we have already noticed 

 in No. X. p. 369, has recently foun^, that when a number of needles are 

 electrified by a single discharge, some of them are rendered slightly magne- 

 tic, some highly so, and others not at all. For any discharge of determi- 

 nate strength, the distance performs the principal part. The magnetic vir- 

 tue goes on decreasing to a certain distance, then it disappears at a given 

 distance ; — it then increases progressively, is again extinguished, and again 

 increases. The distance requisite to produce the maximum and minimum 

 degree of magnetism depends on the strength of the discharge. M. Savary 

 has likewise determined the effects produced by the interposition of screens. 

 —Le Globe, 26th January 1828. 



12. On the variable conducting powers of bodies for Electricity. — Profes- 

 sor Delarive of Geneva has found that the degree of conductibility of bodies 

 for electricity depends on the quantity of electricity which traverses them, 

 so that of two conducting bodies, that which is the best for one electric 

 current may be the worst for either a stronger or a weaker current. 



13. M. Becquerel on the Pyro-electricity of the Tourmaline. >— On the 22d 

 January 1828, M. Arago communicated to the Academy of Sciences the 

 following fact respecting the Tourmaline discovered by M. Becquerel. 



" While the tourmaline is of a certain length it is electrical by heating and 

 cooling ; in a greater length it ceases to be so by heating. In taking cry- 

 stals of different lengths, the phenomena diminish in intensity, and those 

 crystals which are eight centimetres (three inches and l-9th) are neither 

 electrical by heating nor cooling. 



If this law is inversely true, that is for very small lengths, the atoms of 

 the tourmaline ought to acquire a considerable electrical polarity by the smaU 

 lest changes of temperature." 



The powerful pyro-electricity of Tourmaline in the state of i\ie finest dust 

 has been long ago described by Dr Brewster, who has pointed out the 

 'singular contrast between this unexpected property and those of magne- 

 tical and doubly refracting structures. — See this Journal, No. ii. p. 212. 



II. CHEMISTRY. 



14. Analysis of the Gas obtained from the Body of a Cow, inflated in 

 consequence of feeding too freely on Green Food. By M. Plugkr.-^Ac- 

 cording to the observations of M. Pluger, the gas derived from this source 

 had the following properties : — 



Kit was colourless, and of a very disagreeable odour. 



2. It burned slowly with a feeble bluish flame. On plunging a lighted 



VOL. VIII. NO. II. APRIL 18^. A a 



