Naiural'Pkilosophicat Collectiong. 23^ 



tlie two convulsions causes the stronger contraction ; and that, When the finger 

 touches the positive pole, the electricity which traverses the nerves proceeds in a 

 direction contrary to their ramification, and, in place of producing a shock, ocea^ 

 sions the peculiar sensation. 



If two metallic cylinders be covered with wet cloth, and one being held in each 

 hand, contact is then made with thirty or forty pairs of plates, moderately active, 

 besides the shocks which are felt each time the communication is completed, 

 there is a particular sensation in the palm of the hand, communicating with the 

 positive pole. This sensation has been very distinct in some persons sensible to 

 the effect of electricity ; and they compared it to that pricking sensation often 

 felt in the hands or feet when the nerves have been compressed for some time to- 

 getheT.^Bib. Univ. xlii. 287. 



Bromuret of Carbon. The foDowing account of this substance is extracted 



from a work on brome and its chemical combinations, by M. Ch. Loewig. 



Bromuret of carbon may be prepared in two ways. According to the first me- 

 thod, brome is mixed with alcohol at 36° Baumd. The mixture heats strongly, 

 and, if brome Is still added, a moment of sudden effervescence supervenes, ac- 

 companied with disengagement of vapours of hydro-bromic acid and free brome. 

 After the liquid has cooled, there is added an alcoholic solution of caustic potash, 

 until discoloration is produced ; water is then poured in, and the alcohol is eva- 

 porated at a gentle heat. When the liquid begins to cool, there separates a small 

 quantity of a yellow oil, heavier than water, and, immediately after, a concrete 

 crystalline matter. The alcoholic solution may also be diluted with a large quan. 

 tity of water, and, in this manner, the concrete substance equally separates with 

 the oil. 



This combination, however, may be obtained in greater quantity by the follow- 

 ing process. Brome is put along with ether for a certain time, and the mixture 

 is then distilled. At first there only passes hydrobromic acid, and then comes 

 very clear oil, which falls to the bottom of the liquid that has already passed. 

 "When the distillation has been continued for some time, it is interrupted, pure 

 potash is added to the residuum, and it is diluted with water. There is then de- 

 posited a voluminous white mass, which is washed with water upon a filter. It 

 is then melted at a very gentle heat, and allowed to harden by cooling. 



This bromuret of carbon forms white opaque scales, greasy to the touch, like 

 camphor, and friable. Its smell is highly aromatic, resembling that of nitric 

 ether ; its taste is sharp, like that of peppermint. In the fluid state it is transpa- 

 rent and colourless. It bums as long as it is in contact with flame, and disen- 

 gages vapours of hydro-bromic acid. It is heavier than water, melts at a slight 

 degree of heat, evaporates at 100° C, and sublimes under the form of needles, 

 having a pearly lustre. It is but feebly dissolved by water, to which it commu- 

 nicates its smell and taste. When the water is at 50° C. it is dissolved, and at a 

 higher degree it is in part evaporated with the vapour. Alcohol and ether easily 

 dissolve it, and the solutions are not rendered turbid by nitrate of silver. Alkalies, 

 have no action upon it, even at the boiling temperature. Sulphuric, hydrochloric, 

 and nitric acids, have no effect upon it. When the melted bromuret of carbon is 

 submitted to a current of free gas, chloruret of brome is immediately formed. On 

 heating it witli the oxides of iron, copper, zinc, &c., there are obtained metallic 

 bromurets, and carbonic acid gas. By making it pass over these metals in the 

 state of vapour, there are obtained metallic bromurets and charcoal. 



It is to this latter property tliat M. I^ccwig has had recourse for analyzing the 

 bromuret of carbon, whicJi is composed of 9.01 carbon, and 91.99 brome, the 

 atomic wciglit of the latter being =941.1. 



VO^. II. 2 G 



