Benzoic Ac'uL ,"^09 



if it be admitted that a magnet is aa assemblage of electric 

 cunciits vviiich are produced bv an action of the particles of 

 steel upon each other, analogous to those of the elements of a 

 Voltaic pile, and that they move in planes perpendicular to the 

 line wliich joins the poles of the magnet. 



This [.art of his theory he demonstrates, by showing that a 

 magnet may be substituted for rhe electrical conductor, and then 

 two magnets instead of the two conductors, without any differ- 

 ent result, except in the intensitv of the effects, which depend 

 on the force of the magnets in all the cases where two currents 

 act one upon the other in attracting and repelling, or in mutually 

 making each other change directions, by virtue of the attrac- 

 tions and repulsions which exist between them, and which vary in 

 proportion to the cosine of the angle of their directions ; so that 

 tlie attraction of each is changed to repulsion, when this angle 

 becomes obtuse, because the cosines become negative when the 

 angle becomes olituse. 



BENZOIC ACID. 



This acid (which has hitherto been found only in benzoin, storax, 

 balsam of Peru and Tolu, vanilla, cinnamon, and the urine of se- 

 veral graminivorous animals, as cows, horses, camels, rhinoceros) 

 has lately been found, by M. Vogel, crystallized in the Tonquin 

 lean (employed to give an agreeable flavour to snuff) between the 

 skin and the kernel. These crystals melt at a moderate heat 

 into a transparent liquid, which suddenly shoots out into stars 

 on cooling, and then becomes a crystallized mass. In a higher 

 temperature it sublimes, and deposits itself in fine brilliant 

 needles, which have a smell similar to that of the bean. A con- 

 centrated solution of these needles in alcohol reddens litmus pa- 

 per, and becomes milky when mixed with water. These needles 

 when saturated with ammonia form a salt which precipitates iron 

 with a brown colour. In a word, they possess all the charac- 

 ters of benzoic acid. 



M. Vogel has also found benzoic acid in the trifolhim melt- 

 lolus ojficinalis by digesting them in alcohol raised to the boiling 

 temperature. On cooling, it precipitated a fatty substance, and 

 in a few days long crystals of benzoic acid appeared in the liquid. 

 To get rid of the fatty matter, the whole was digested in boiling 

 water, and then filtered. The Hquid with the acid passed the 

 filter, and, on l)eing slightly evaporated, yielded the acid in cry- 

 stals. According to M. Vogel, the ([uantity of benzoic acid in 

 these flowers is so abundant that it may be extracted from them 

 with profit for sale. — {Gilbert's Annalen.) 



THE 



