Philosophical Transactions. 375 



far from accelerating them, five out of six upon which he expe- 

 rimented were actually retarded, and the acceleration of the sixth 

 was doubtful : he shews that much depends upon the position of 

 the balance in regard to the iron. All these experiments prove 

 that chronometers should be as carefully secluded from the 

 action of any partial mass of iron, as the compass itself; and 

 Mr. Barlow suggests, that as much of the iron of a ship is 

 hidden, the best way of ascertaining a proper place for a chro- 

 nometer will be to set down a compass in the situation designed 

 for it, and to observe and compare the direction of its needle 

 with that of an azimuth compass on deck, while the vessel is on 

 different tacks, and if the disagreement between the two be 

 considerable, to select another situation. 



13. On the Peculiarities that distinguish the Manatee of the 

 West Indies, from the Dugong of the East-Indian Seas. By 

 Sir EvERAUD Home, Bart., V. P. R. S. 



This is a short comparative description of the anatomy of 

 these animals, illustrated by four plates from the accurate pen- 

 cil of Mr. Clift. The first of these shews the external form of 

 the Manatee, which has a broader tail and greater lateral ex- 

 tension of the ribs than the dugong ; its habits of life place it 

 between that animal and the hippopotamus ; it has no tusks, 

 and feeds upon plants growing at the mouths of large rivers. 

 The second plate is a general view of the skeleton ; the third, 

 a representation of the stomach ; and the fourth exhibits the 

 peculiarities of its c£Bcum. 



14. On a new Componnd of Chlorine and Carbon. By Richard 

 Piiii.Lirs, F. R. S. E., cSc, and M.Faraday, Chemical 

 Assistant in the Royal Institution. 



This compound was accidentally found by M. Julien, a nitric 

 acid manufacturer of Abo, in Finland, amongst the products of 

 his processes. It is a soft wliite tasteless solid ; insoluble in 

 water; vcdatiie and in(lan>mable; insoluble in acids and alcalis; 

 and when raised in vapour over hot mercury, and detonated with 

 excess of oxygen, chloride of mercury and carbonic acid arc 

 the results. 



The analytical details of this paper prove the substance de- 

 scribed to consist of one portion of chlorine =i .33.5 and two of 

 carbon == 11.4, so that it is intermediate between the proto- 

 riiloride and perchloridc of carbon, previously descriljed by 

 Mr. Faraday. Ail endeavours to form this chloride, or to con- 

 vert it into tlic other chlorides, have proved iiioHeclii il ; yet the 

 snialiness of the (juantity of this compound in possession of the 

 autliois prevented their pursuing this investigation to the ex- 

 tent tluy could have desired. 



