jaa Scientific News, Accounts of Books, G?e' 



gives the formulse i— — to calculate the momentum of the magnetic force referred to the 



arm of a lever of one millimeter in length. The length of the needle was 427 millimetres, 

 its breadth 13, and its weight 88753 milligrammes. It was fufpended horizontally by a 

 thread of filk in a box well clofed, and it made 30 ofcillations in 286 feconds, and by ap- 

 plying thefe data to the preceding formula, Cit. Coulomb finds that the logarithm of the 

 momentum of the horizontal magnetic force is 4,1740. 



Cit. Coulomb having placed his needle in a clip, having knife edges, which refted on 

 two cylinders of glafs, in the manner of the beam of a balance, endeavoured firft to bring it 

 to an equilibrium in an horizontal fituation coinciding with the magnetic meridian, by 

 placing the edges in a proper manner, and when they were fufficiently near the point where 

 the equilibrium took place, he completed it by the addition of fmall weights. He then 

 reverfed the poles of the needle by the magnetic touch, but without altering the pofition of 

 the clip, and again bringing it to an equilibrium in this new ftate, the fum of the momenta 

 of the additional weights placed in thefe two operations gave him the double of the momen- 

 tum of the vertical component parts of the magnetic force, valued at 2H_2, The refult of 



2 



this force, and of the horizontal force, is inclined 68° 9'. 



In repeating thefe operations three times, Cit. Coulomb obtained fucceffively 68" 9' ; 

 68° 13'; and 68° 11'. Though the differences of thefe refults are very trifling, he does 

 think they are to be entirely attributed to errors in the obfervation ; for he is affured that 

 they do not amount to fo much. It is poffible that the needle is fubjefl to variations ia the 

 vertical fimilar to thofe which are known to take place in the horizontal plane. 



Bulletin de la Soc, Phil. No. 31. A>u 8. 



New ProduSfion of Ammonia, 



Mr. Lampadius, at Freyberg, has obferved that when crude, or which is better, purified 

 acidulous tartritc of pot-afli, is heated till no more fumes or flame appear, and water is 

 then added to it, ammoniac is produced. This fa£t is belt obferved when heated mafs is 

 flill warm (about 120 R.) 



The experiment may be performed with the fame tartrite repeatedly, or at lead as long 

 as any carbonaceous matter remain, by merely heating it, and then wetting it with a few 

 drops of water. Carbon mechanically joined to pot-afh does not produce this effed ; but 

 the acidulous oxalate of pot-a(b, treated in the fame manner, affords a fimilar refult. 



CrelPs Annals of Chemijry, No, B, 1800. 



Upon 



